A man has been arrested after a truck was driven into a crowd on a busy shopping street in Stockholm before crashing into a department store, killing four people, in what the prime minister described as a suspected terrorist attack.
At least 15 others were wounded when a man in a mask hijacked a beer truck that was making a delivery on Drottninggatan (Queen Street) in Stockholm on Friday, local time.
Witnesses described seeing the truck swerve from side to side in an effort to deliberately mow people down.
Swedish police said they had arrested one man late on Friday in connection with the attack, but they had not ruled out the possibility other attackers were involved.
The man had some minor injuries and had admitted responsibility, the Aftonbladet newspaper said, citing several unnamed sources.
Hours earlier, police issued an image of a man they said they wanted to speak to in connection with the incident.
"We went public with information and a picture of a person that we were interested in," regional police official Jan Evensson said.
"The person who is arrested resembles that description which means we have particular interest in him in regard to the ongoing investigation."
Mats Lofving, the head of Swedish police's National Operations Department, said the picture, which appeared to be CCTV footage, was taken around the time of the attack.
The grainy image shown by police showed a man wearing a jacket with a dark hood over a bright T-shirt and dark trousers.
Stockholm streets locked down
Part of central Stockholm was cordoned off and the area evacuated, including the main train station, after the incident. All subway traffic was halted on orders from the police.
The parliament building and the government headquarters were both locked down, according to a radio report shared by the official Sweden Twitter account.
"Sweden has been attacked. Everything points to the fact that this is a terrorist attack," Prime Minister Stefan Lofven said during a visit to western Sweden. He was immediately returning to the capital.
"These kinds of actions will never succeed. We know that our enemies are these atrocious murderers and not each other," he said.
"Our message will always be clear: you will not defeat us, you will not govern our lives, you will never, ever win."
King Carl Gustaf, Sweden's head of state, expressed his horror at the attack.
"Our thoughts are going out to those that were affected, and to their families," he said in a statement from the royal palace.
'It was terrible to see'
The truck smashed into the Ahlens department store near the centre of the city just before 3pm local time.
Bloody tyre tracks showed the path of the truck, which was stolen by a masked hijacker while making a beer delivery to a tapas bar further up Drottninggatan, according to Spendrups Brewery spokesman Marten Lyth.
National news agency TT said those hurt included the delivery driver, who had tried to stop the hijack.
"We were standing by the traffic lights at Drottninggatan and then we heard some screaming and saw a truck coming," a witness who declined to be named told Reuters.
"Then it drove into a pillar at (department store) Ahlens City, where the hood started burning. When it stopped we saw a man lying under the tyre. It was terrible to see," said the man, who saw the incident from his car.
Sweden's TT news agency quoted the company's communications director, Marten Lyth, as saying "someone jumped into the driver's cabin and drove off while the driver unloaded."
Authorities imposed sweeping security measures, closing off streets and shutting down public transport lines in scenes similar to those seen in London when a car was driven into pedestrians on Westminster Bridge last month.
One witness, named only as Anna, told Stockholm newspaper Aftonbladet that she saw hundreds of people running.
"They ran for their lives," she said. "I turned and ran as well."
John Backvid was at the scene shortly after the truck hit pedestrians near the shopping mall.
He said he first noticed smoke hanging in the air, then realised there were injured people on the ground.
"Some people were on the ground doing CPR ... I was standing there for maybe 30 seconds before the police car arrived," Mr Backvid told the BBC.
Police soon began to clear the area, he said, owing to concerns the burning truck could ignite a gas canister on a nearby street cart.
"They began to scream about gas, and I ran away with a lot of other people. It was very chaotic. The police were very quick," Mr Backvid said.
He said he did not see the driver of the truck.
"My initial thought was this truck must have been driving way too fast," Mr Backvid said.
Soon, he said, police with submachine guns flooded to the area, "driving down the street quite quickly and telling everyone to get out of the city."
'Sense of sheer panic'
Another witness, Annevi Petersson, told the BBC she had just walked into a shop on the pedestrian boulevard when the truck ploughed into several people.
"I heard the noise, I heard the screams. I saw the people as I walked out immediately," she said.
She said she saw a dead dog on the footpath, and then saw the dog's distraught owner clutching the dog and screaming.
There was a "sense of sheer panic" on the street, and store owners locked their customers inside.
"It was the noise, then everything got quiet, then everyone started screaming and crying," she said. "There was blood everywhere, there were bodies on the ground everywhere."
Television footage showed smoke coming out of the department store, while photos showed flames coming from the truck's cabin.
Over the border in Norway, police in the largest cities and at Oslo's airport were ordered to carry weapons until further notice, Norwegian police said in a tweet.
Police officers in Norway do not usually carry guns on them.
In Finland, police increased patrols in the capital Helsinki.
Attack latest to hit Nordic region
The attack was the latest to hit the Nordic region after the 2015 shootings in Copenhagen, Denmark, that killed three people and the 2011 bombing and shooting by far right extremist Anders Behring Breivik that killed 77 people in Norway.
Sweden has not been hit by a large-scale attack, although in December 2010 a man blew himself up in central Stockholm in a failed suicide attack.
Swedish authorities raised the national security threat level to four on a scale of five in October 2010 but lowered the level to three, indicating a "raised threat", in March 2016.
Several attacks in which trucks or cars have driven into crowds have taken place in Europe in the past year.
On March 22, a man in a car ploughed into pedestrians on Westminster Bridge in London, killing four, and then stabbed a policeman to death before being shot by police.
Islamic State claimed responsibility for both an attack in Nice, France, last July, when a truck killed 86 people celebrating Bastille Day, and one in Berlin in December, when a truck smashed through a Christmas market, killing 12 people.
The world responds
The European Union offered Sweden support and solidarity on Friday.
"An attack on any of our member states is an attack on us all," said EU chief executive Jean-Claude Juncker.
"One of Europe's most vibrant and colourful cities appears to have been struck by those wishing it – and our very way of life – harm.
"We stand shoulder to shoulder in solidarity with the people of Sweden and the Swedish authorities can count on the European Commission to support them in any which way we can."
EU President Donald Tusk also tweeted his support.
German government spokesman Steffen Seibert also reacted to the news.
"Our thoughts are with the people in Stockholm, the injured, relatives, rescuers and police. We stand together against terror," he said in a tweet.
Sweden's Nordic neighbours also expressed their horror.
"Terrible news from Stockholm. Our thoughts are with our neighbours and friends in Sweden," Finland's Prime Minister Juha Sipila wrote in Swedish on his Twitter account.
Danish Foreign Minister Anders Samuelsen, speaking in Vienna, called for more cooperation between countries to combat attacks.
"It's so horrible to learn about this terror attack ... It's horrible, it's disgusting and we have to fight this terror appearing in Europe," he said.
"And one thing we can do is to cooperate even closer on exchanging data, exchanging information about what we learn of those terror cells or terrorists."
- with AP, Reuters
