So the assault on an Algerian gas complex which aimed to free hostages from Islamists retaliating for France's military action in Mali has ended after hours of tense uncertainty.
A photograph taken on January 17, 2013 of a collect image issued by the family of Stephen McFaul, an Irish passport holder taken hostage by Islamist kidnappers at a gas field in Algeria, with his sons Dylan (L) and Jake. The 36-year-old Belfast man is no longer being held and is "safe and well", the Irish government said.
It is still not clear how many people have died.
Kidnappers have claimed that 34 hostages and 15 Islamists died in an Algerian military air strike but there is no official death toll at this stage.
People from the US, Britain, France, Ireland, Norway and Japan are among those thought to be caught up in the situation, along with many Algerian workers.
More details of what happened are likely to emerge in the coming hours -- make sure you follow AFP's coverage for all the news on this and other stories as it breaks.
2015 GMT: The latest reports from APS are not yet giving a final death toll from the Algerian army's operation, which has now ended.
The country's Communication Minister Mohamed Said confirmed earlier that there had been some deaths but added that a number of other hostages had been freed.
2008 GMT: We're waiting for further news on the end of the hostage rescue operation, as reported by Algeria's APS news agency.
But if the operation is over, a sense of relief is likely to be tempered by trepidation in countries whose citizens are involved about what might have happened to them.
1956 GMT: HOSTAGE RESCUE OPERATION OVER: APS NEWS AGENCY
1942 GMT: British foreign minister Alistair Burt has gone further than PM Cameron in warning of the likelihood of bad news to come from Algeria.
"Although details have yet to become final, I'm afraid we should be under no illusion that there will be some bad and distressing news to follow from this terrorist attack," Burt told the BBC.
1930 GMT: For those just joining us, here is a quick recap of the latest breaking events in the fast-moving Algerian gas field hostage crisis.
- Governments from around the world have been voicing concern over what is happening after Islamists said an army air strike has killed 34 hostages and 15 Islamists. There is no official death toll although Algeria says there have been some deaths and that the operation is ongoing;
- Japanese PM Shinzo Abe, whose country has citizens on the ground, has called his Algerian counterpart to urge a halt to the operation, voicing "strong concern";
- Britain has said it was only told about the operation when it was under way and "would have preferred to have been consulted in advance". Prime Minister David Cameron has postponed a key speech scheduled for Friday on European policy and warned of possible "further bad news."
1920 GMT: Algerian minister Said has now said that his country's army has "neutralised" some Islamist gunmen who were fleeing the gas plant and heading for a neighbouring country.
He has been speaking about the crisis on national TV.
1855 GMT: Fresh comments also coming in from Norway's Prime Minister Jens Stoltenberg in Oslo.
He says there is still no "reliable information" on nine of its nationals working at the gas plant.
Twelve employees from Norwegian oil group Statoil, which jointly operates the gas field with BP and state-run Algerian energy firm Sonatrach, were previously reported missing.
1848 GMT: More on those remarks -- Algeria's Communication Minister Mohamed Said has been giving the first official comments on the operation on national TV.
"The operation is ongoing," he says, adding that "several people" were killed or wounded but an "important number" of hostages were freed.
1844 GMT: ALGERIAN MINISTER CONFIRMS DEATHS IN HOSTAGE CRISIS, SAYS OPERATION ONGOING
1843 GMT: British PM Cameron has just postponed a highly sensitive, long-awaited speech in the Netherlands on his European policy planned for Friday due to the crisis in Algeria.
He also warned that his country "should be prepared for the possibility of further bad news" in televised comments.
1828 GMT: A string of governments from around the world expressing concern over the situation in Algeria amid a still unclear picture of what is actually going on and how many people have been killed.
Particularly interesting to note that countries like Japan and Britain are going public at this stage with their critiques.
The US seems to be choosing to remain more guarded for now.
1808 GMT: US Secretary of State Hillary Clinton is urging all of the country's embassies and firms in north Africa to review their security arrangements.
1805 GMT: More on those comments made by French President Francois Hollande.
He insists the hostage situation in Algeria will have no impact on France's military action in Mali, despite the militant attackers indicating their action was in response to this.
"What is happening in Algeria provides even more justification for the decision I took in the name of France to come to the aid of Mali," Hollande says.
1753 GMT: On the markets, oil prices are up on news of the uncertain situation at the Algerian gas field.
Brent North Sea crude for delivery in March climbed 73 cents to $110.41 a barrel in late London trading.
New York's main contract, light sweet crude for February gained $1.05 to $95.29 a barrel.
1744 GMT: Meanwhile in the US, White House spokesman Jay Carney did not say whether Washington was told in advance of the operation by the Algerian government.
British PM David Cameron's spokesman said earlier that he was only informed of the operation once it had got under way and that Britain "would have preferred to have been consulted in advance."
1738 GMT: Japanese Prime Minister Shinzo Abe has also called his opposite number in Algeria to request a halt to the operation, government spokesman Suga says.
"Prime Minister Abe told him that the government of Japan has asked the Algerian government to put the highest priority on people's lives and expressed his strong concern that such an operation is underway," Suga tells reporters in Tokyo.
"He urged him to halt such actions."
1728 GMT: FRENCH PRESIDENT HOLLANDE SAYS HOSTAGE CRISIS UNFOLDING IN 'TERRIBLE CONDITIONS'
1727 GMT: More on those comments from the Japanese government.
Vice foreign minister Minoru Kiuchi is in Algeria and has met the country's foreign minister.
Kiuchi "urged the Algerian government to stop the operation immediately", chief cabinet secretary Yoshihide Suga says in Tokyo.
Japanese citizens are among the foreigners who have been taken hostage.
1720 GMT: US CONCERNED ABOUT HOSTAGE SITUATION, SEEKS 'CLARITY'
1719 GMT: JAPAN URGES ALGERIA TO HALT MILITARY OPERATION 'IMMEDIATELY': MINISTER
1705 GMT: A quick rundown of events today so far:
- The Algerian military launched a bid to regain control of a gas complex in the country's remote desert, where an Islamist group took scores of foreign hostages a day earlier; hundreds of Algerians were also at the site, but it is unclear if they were treated as hostages;
- The military apparently launched air strikes and a ground offensive, which a spokesman for the hostage-takers -- linked to the regional branch of Al-Qaeda -- said had killed 34 hostages and 15 kidnappers;
- Algeria's state news agency reported that nearly 600 Algerian workers and four foreign hostages -- two from Britain, one from France and one from Kenya -- were freed during the operation;
- The Irish government said a Northern Irish man was freed, and his family confirmed this;
- Foreign leaders including those of Britain, Norway and France were informed of the military raid but only once it was underway.
Stay with us for more updates.
1656 GMT: The parents of Northern Irish hostage Stephen McFaul, who is now free, tell Britain's Sky News there will be "a big celebration" in west Belfast tonight.
"The last 48 hours have been hell," says his father Christopher McFaul. He says he was "delighted" to hear of the release of his son, an electrical engineer with a lot of experience in west Africa.
"I feel sorry for the other hostages that are still there. We don't know what's happened to them, and the ones who have been killed -- I feel sorry for their families," Christopher McFaul adds.
Stephen's mother Marie says: "He'll have coped very well. He'll have put his business head on and just got on with it."
1647 GMT: Frantic diplomacy is taking place between countries involved in the crisis. The office of Britain's prime minister tweets that "PM has spoken to (US President Barack) Obama and (French President Francois) Hollande".
1645 GMT: US news channel CBS is reporting that an unarmed American Predator drone is now overhead at the site, allowing US authorities to get an independent look at the scene.
1637 GMT: The office of Britain's prime minister says he was not informed of Algeria's military intervention at the site, and made clear he would have preferred to know in advance.
But the Algerians said they had to act "immediately", his spokesman says.
"The Prime Minister is extremely concerned. It is a very grave and serious situation."
1625 GMT: A bit of background on the Tiguentourine gas facility, where the military operation is ongoing: it's an isolated site, about 40 kilometres (25 miles) from the town of In Amenas close to the border with Libya.
The gas field has been developed since 2006 by British energy giant BP, Norway's Statoil and Algerian firm Sonatrach.
About 700 people, mostly Algerians, work in the complex, most of them as subcontractors, industry sources have told AFP.
The complex includes a residential base where workers live, managed by Marseille-based French firm CIS Catering. A security camp is between the plant and the base, accessible only with a pass.
1623 GMT: Algerian gas deliveries to Italy fell by over 10 million cubic metres a day, a spokesman for Italian gas transport group Snam says, amid the gas plant hostage crisis.
The gas flow on the Transmed pipeline has dropped to 62 mcm a day from the usual 75.2 mcm, the spokesman said.
1617 GMT: The Irish passport-holder freed from the kidnappers in Algeria has been named in media reports as 36-year-old Stephen McFaul from Belfast in Northern Ireland.
It is not clear whether he escaped or was freed. (Although Northern Ireland is part of the United Kingdom, its residents are entitled to hold both British and Irish passports.)
Earlier on Thursday, McFaul's family had appealed for his safe release.
1608 GMT: Norway's Prime Minister Jens Stoltenberg and Foreign Minister Espen Barth Eide are to hold a press conference at 7:00pm local time (1800 GMT) with an update on the In Amenas hostage situation, AFP's Pierre-Henry Deshayes reports from Oslo.
Norwegian firm Statoil is involved in the gas complex, and twelve of its employees -- nine Norwegians and three Algerians -- are thought to be caught up in the hostage crisis.
1600 GMT: A foreign diplomat in Algiers has confirmed to AFP that the rescue mission "did not go too well for the hostages," adding that the operations were ongoing in the late afternoon.
The kidnappers earlier spoke of 34 captives and 15 hostage-takers being killed as Algerian military forces attacked the complex.
Meanwhile, the group behind the hostage-taking, calling itself "Signatories for Blood", is led by veteran Algerian-born Islamist fighter Mokhtar Belmokhtar, a former leader of Al-Qaeda in the Islamic Maghreb, who was ejected from the group last year.
The one-eyed jihadist has been blamed for previous abductions and killings of both Algerians and foreigners.
He has been nicknamed "The Uncatchable" by French intelligence -- as well as "Mr Marlboro" for his cigarette smuggling.
1543 GMT: In Northern Ireland, local MP Paul Maskey tweets: "Just out of the family home of the local man who was held hostage in Algeria. Brilliant news on his release. Family are delighted."
The Irish Republic's foreign ministry earlier reported that the man -- who holds an Irish passport -- was no longer a hostage and had contacted his family.
1534 GMT: As the situation changes fast on the ground in Algeria, France says it has won support from EU nations for its military campaign in Mali, where it is helping government troops fight an Islamist rebellion in the north.
French Foreign Minister Laurent Fabius said after talks that "all the countries expressed their solidarity with Mali and support for France's action".
Many planned to offer logistical or material support to back efforts by France and African troops to rout Islamist guerrillas, he said.
France's intervention, beginning last week, in the long-running Malian crisis appears to have sparked the Algerian hostage situation.
1537 GMT: More from the spokesman for the kidnappers, who tells the ANI news agency: "Warplanes and ground units have begun an operation to take the complex by force."
The spokesman threatens to "kill all the hostages if the Algerian forces succeed in entering the complex".
1527 GMT: Among those freed appears to be a hostage from Northern Ireland, who also holds a passport from the Irish Republic.
Ireland's foreign ministry says it "wishes to advise that the Irish national held hostage in the Amenas gas-field compound has made contact with his family and is understood to be safe and well and no longer a hostage".
1522 GMT: ALGERIA LAUNCHES GROUND ASSAULT ON COMPLEX WHERE HOSTAGES HELD, SAYS KIDNAPPER
1519 GMT: 600 ALGERIANS FREED IN ARMY RESCUE OPERATION: STATE NEWS AGENCY
1512 GMT: The Algerian army has freed four hostages -- two Britons, a Frenchman and a Kenyan, the country's official news agency APS says, citing local sources.
An unspecified number of people were killed in the rescue operation, this report says.
1505 GMT: More from BP: the energy giant now says it is evacuating "a group of non-essential workers" out of Algeria.
"The situation remains unclear and we continue to seek updates from the authorities," its statement adds.
"Sadly, there have been some reports of casualties but we are still lacking any confirmed or reliable information. There are also reports of hostages being released or escaping."
1458 GMT: Oil giant BP, which part-runs the gas complex, says it has been informed by the British and Algerian governments that "the Algerian army is attempting to take control of the In Amenas site".
1455 GMT: Algerian media earlier reported that 15 foreigners and 30 Algerian hostages had escaped the complex, but authorities could not confirm this and it does not appear to tally with the death tolls now emerging from the hostage-takers.
1451 GMT: Some more details on the alleged survivors of the Algerian air strike, again coming from a spokesman for the kidnappers, speaking to Mauritania's ANI news agency.
"Three Belgians, two Americans, one Japanese and one Briton survived a raid by Algerian airplanes on the place they were being held, the spokesman said, adding a call for the management of the gas field to "aid the wounded hostages".
The hostage-takers have said 34 captives and 15 kidnappers were killed in the strike.
1444 GMT: Speaking after emergency talks with EU foreign ministers, Mali's Foreign Minister Tieman Coulibaly says the Islamists linked to Al-Qaeda in the north of the West African state are a "global threat."
Given the number of nationalities involved in the Algerian crisis -- which kidnappers have said is a reprisal for French involvement in the Mali conflict -- this is a statement likely to be taken seriously.
"Today, it's a question of mobilising the international community in its entirety to come to our help in our country, but also to come to the aid of the whole region because what is happening in Mali represents a global threat," Coulibaly tells a press conference.
With reference to the ongoing raid on athe Algerian gas field, the minister says "jihadists" in the region are part of an international "drug trafficking" organisation, a "criminal enterprise" that has "nothing to do with politics" and is a "genuine threat to civilisation."
1443 GMT: The Norwegian government, like the British and French, is now confirming an ongoing military operation at the site.
1441 GMT: SEVEN HOSTAGES, INCLUDING TWO AMERICANS, STILL ALIVE IN ALGERIA: KIDNAPPER
1440 GMT: The latest claims from a spokesman for the kidnappers, coming via Mauritania's ANI news agency, also include the allegation that the leader of the Wednesday hostage-taking, Abu al-Baraa, has been killed in the army assault.
WELCOME TO AFP'S LIVE REPORT as Algerian troops launch strikes on a gas complex where Islamists are holding dozens of foreigners to avenge a French-led offensive in Mali.
A group calling itself the "Signatories for Blood" has claimed responsibility for the hostage-taking on Wednesday at the In Amenas gas field near the Libyan border.
The ANI news agency is now reporting, citing a spokesman for the kidnappers, that an Algerian air strike killed 34 hostages, some of them Westerners, and 15 of their Islamist kidnappers -- but these claims have not been independently confirmed.
The spokesman said that Westerners were among the dead, and that aircraft attacked the kidnappers when they tried to "transport some of the hostages in vehicles to a location to the south".
Meanwhile, the French and British governments have confirmed that an operation is underway at the gas field, but have not specified details.
One of the kidnappers has previously told Al-Jazeera that about 41 foreigners are being held, including people from Austria, Norway, France, the United States, Britain, Romania, Colombia, Thailand, the Philippines, Ireland, Japan, South Korea, and Germany.
Dozens of Algerians are also among the hostages.