STOCKHOLM - A man steered a stolen beer truck into a crowd of people and then rammed it into a department store, killing at least four people in what officials were calling a terrorist attack in the heart of Stockholm on Friday afternoon.
"Sweden has been attacked. All indications are that it was a terrorist attack," Prime Minister Stefan Lofven said in a statement.
Swedish police arrested one man "whom we are particularly interested in" in the deadly stolen beer truck attack in Stockholm.
Police released this photo of the man, now under arrest, as the main suspect in the 'lone wolf' attack.
Jan Evensson from the Stockholm police told a news conference late Friday (early Saturday Thailand time) the man was arrested in Marsta, a northern Stockholm suburb close to the city's international airport, Arlanda.
He said the man was "in the vicinity" of the truck crash that killed four people and wounded 15 others on a pedestrian street in the Swedish capital.
The suspect was spotted by a police patrol and was in a police photo released earlier Friday wearing a greenish hood at the top of an escalator.
Stefan Hector of the Sweden's national police said, "We have a working hypothesis this is an act of terror."
Evensson urged people not to go into central Stockholm for the time being.
The authorities said they did not know if it had been an isolated assault, or something bigger. The Swedish intelligence agency said "a large number" of people had been wounded.
Mats Loefving, head of the national operative department of the Swedish police, said, "This is now declared a national security event," adding that officers across the nation were on heightened alert.
The Swedish Parliament was on lockdown, according to news reports. Train service in and out of the city grounded to a halt, and the police, who blocked off the affected area, urged people to stay at home and avoid the city centre.
Police said the first emergency call came in around 2.50pm local time (7.50pm Thailand time) as the attack unfolded in Drottninggatan, Stockholm's busiest shopping street.
Witnesses described a scene of panic and terror.
"I saw hundreds of people running; they ran for their lives" before the truck crashed into the Ahlens department store, a witness identified only as Anna told the newspaper Aftonbladet.
Katarina Libert, a 32-year-old freelance journalist, was trying on clothes at the department store when she heard a boom and the walls shook.
At first, she said, she thought the noise was people moving things around the store, but then the fire alarm went off and staff members told her and other shoppers to get out of the building.
"We were running, we were crying, everyone was in shock," Libert said. "We rushed down the street, and I glanced to the right and saw the truck. People were lying on the ground. They were not moving."
Libert, who followed others as they were guided by officials to shelter, added, "My sister-in-law and some friends are close to the scene and at lockdown, can't leave their office."
She said that she usually avoided busy areas that could be potential terrorist targets, but that she had decided to take the Friday afternoon off to do some shopping.
"Some people felt that this was just a matter of time," she said. "Paris, Brussels, London and now Stockholm. I just had a feeling something like this would happen."
The rear of the stolen beer truck protrudes after it crashed into a department store in Stockholm on Friday. (Reuters Photo)
Earlier report
A hijacked beer truck crashed into a department store in Stockholm on Friday afternoon, killing at least two people in what Sweden's prime minister called "a terror attack". One man was arrested.
People in the downtown area fled in panic, and Stockholm's Central Station for trains and the subway, which is a few hundred metres from the scene, was evacuated.
The Swedish broadcaster SVT said at least five people were killed while Swedish radio reported three dead. Police issued a statement that they had accounted for four dead.
Prime Minister Stefan Lofven said everything indicated that the incident was "a terror attack". He said one person was arrested but gave no further details.
"There are deaths, and many injured," said Nina Odermalm Schei, a spokeswoman for the state intelligence agency Sapo.
Police said there were no indications of shots fired in the area, as SVT had reported earlier. There was no immediate claim of responsibility for the attack.
Live television footage showed smoke coming out of the Ahlens department store on Drottninggatan Street, which the truck smashed into. The department store is part of Sweden-wide chain. The building includes several stores at street level.
"We stood inside a shoe store and heard something ... and then people started to scream," witness Jan Granroth told the newspaper Aftonbladet. "I looked out of the store and saw a big truck."
The newspaper said the Swedish brewer Spendrups reported that one of its trucks had been hijacked earlier in the day.
The incident occurred just before 2pm local time (8pm Thailand time) on Drottninggatan, the city's biggest pedestrian street, near the central subway station.
Thick smoke was rising from the scene, while video images showed an area blocked off by police and crowds gathering. Helicopters could be heard hovering over central Stockholm, and a large number of police cars and ambulances at the scene, witnesses said.
Friday's crash was near the site of a December 2010 attack in which Taimour Abdulwahab, a Swedish citizen who lived in Britain, detonated a suicide bomb, killing himself and injuring two others.
Abdulwahab had rigged a car with explosives in the hope that the blast would drive people to Drottninggatan where he would set off devices strapped to his chest and back. The car bomb never went off, and Abdulwahab died when one of his devices exploded among panicked Christmas shoppers.
Vehicles have become common weapons in recent extremist attacks.
Last month, in an attack claimed by the Islamic State, a man drove into a crowd on London's Westminster Bridge, killing three people and injuring many others before stabbing a policeman to death. He was shot dead by police. A fourth person, a woman thrown into the Thames by the force of the car attack, died on Thursday.
IS also claimed responsibility for a truck attack that killed 86 people in Nice, France, last July during a Bastille Day festival, and for another truck attack that killed 12 people at a Christmas market in Berlin this past December.