A man rammed a car loaded with a homemade bomb into the headquarters of Spain's conservative ruling party on Friday but no blast nor injuries resulted, police said.
Police block the entrance of Genova street in Madrid close to the Spanish Popular Party's headquarters after a man rammed his car with two gas cylinders into the building on December 19, 2014
The car contained gas canisters and nearly six kilos (13 pounds) of ammonium nitrate, a common fertiliser compound, a police spokeswoman told AFP.
Police were investigating the suspect's possible motives amid conflicting reports over his identity.
"It was a big load of explosives which could have caused serious damage to the ground floor and might have affected neighbouring buildings," the spokeswoman said.
Along with the explosives was a 90-minute timer that was not activated and a detonator made from matches, she said.
Photographs from inside the building showed the dark blue four-door car covered in wreckage after coming to a halt in the lobby.
No one was hurt but rush-hour traffic was disrupted in central Madrid where the Popular Party building is located.
Police arrested the driver of the car at the scene after the car crashed shortly before dawn.
They identified him as Daniel Perez Berlanga, 37, from near Teruel in eastern Spain.
They said he told police who arrested him that he was a bankrupted businessman, but that investigations soon revealed he was unemployed and had never had a business.
Some sources had said he was thought to be mentally ill but a police spokeswoman later said he "has not been diagnosed or treated for any mental illness".
Deputy Prime Minister Soraya Saenz de Santamaria said the suspect's mental health "will be for the investigators to determine".
- 'Terrorism' ruled out -
Police cordoned off a large area around the party building, causing traffic jams and blocking people from getting to work for several hours.
"There was a cordon and police told me I couldn't pass because there had been some kind of attack," said Giuseppe Di Bella, a 28-year-old lawyer who works opposite the party building.
"They said there was a car carrying gas cylinders. It's a bit much for a Friday morning."
Several metro stations were closed and some lines were suspended for several hours before resuming normal service, police said.
After the alert was lifted, Prime Minister Mariano Rajoy, leader of the party, visited the headquarters.
The deputy leader of the party, Maria Dolores Cospedal, said that "the possibility of a terrorist attack has been ruled out."
"We wish to send a message of calm and thank the police for their quick and efficient response," she said in a statement.
The party's parliamentary spokesman Rafael Hernando said: "It obviously causes great alarm that someone could attack a political party -- mine or any other."
Since coming to power in 2011, Prime Minister Mariano Rajoy and his Popular Party have imposed tough economic cuts that they say were needed to drag Spain out of an economic crisis.
Rajoy says Spain is now recovering, but the unemployment rate remains extremely high at close to 24 percent.