Local media claim the suspect is a 39-year-old man of Uzbek origin and a supporter of the so-called "Islamic State." He allegedly drove a truck into a crowded Stockholm department store, killing four people.
Swedish police confirmed on Saturday they had captured the driver of a truck that ploughed into a crowd of people in a busy Stockholm department store on Friday.
They arrested a man in a northern Stockholm suburb on "suspicion of terrorist crime" on Friday, after four people were killed and 15 wounded in what the prime minister described as a terrorist attack.
"The person in question has been arrested as the culprit ... in this case the driver," police spokesman Lars Bystrom said on Saturday.
"Then, there can be other people who are associated with him, but we do not know that at the current time," Bystrom added.
Local media reported the suspect in custody was a 39-year-old Uzbek. Police declined to comment on the information. Police had earlier circulated an image of a man wearing a grey hoodie after the Drottninggatan (Queen Street) attack using a hijacked beer truck.
A man hijacked the beer truck as it made a delivery to a nearby tapas restaurant and then drove it into a crowd
Stockholm tabloid "Aftonbladet" and public broadcaster SVT News reported that police found explosives in the truck and set up a 200 meter (218 yard) cordon.
SVT reported the device was in a bag, but did not explode and the suspected driver had sustained burns.
"I turned around and saw a big truck coming towards me. It swerved from side to side. It didn't look out of control. It was trying to hit people," Glen Foran, an Australian tourist in his 40s, told news agency Reuters.
"It hit people; it was terrible. It hit a pram with a kid in it, demolished it," he said.
Police arrested another suspect in the suburb of Hjulsta but did not release further details
Central Stockholm and the main rail station remained cordoned off late on Friday. All subway traffic was halted on police orders and government offices were closed.
Bloody tire tracks revealed the path of the truck, which was stolen by a masked hijacker while it was making a beer delivery to a tapas bar, according to Spendrups Brewery spokesman Marten Lyth. National news agency TT said the delivery driver tried to stop the hijacking and was hurt in the process.
"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 tire. It was terrible to see," said the man, who saw the incident from his car.
Authorities shut down central Stockholm in the wake of the attack
'You will not defeat us'
"Our message will always be clear: you will not defeat us, you will not govern our lives, you will never, ever win," Prime Minister Stefan Lofven told a news conference.
Crown Princess Victoria and Prince Daniel visited the site to lay roses and express support.
"I feel a huge sadness and an emptiness. But I still feel a strength among a society that has shown a tremendous strength," the princess was quoted by "Aftonbladet" as saying. "The fact that we are united and that Swedish society is based on the tremendous trust, community spirit and cohesion, means we will come out stronger from this."
No groups had claimed responsibility for the attack. Police said security at Swedish borders had been heightened and did not rule out the possibility other attackers were involved.
Another man was reportedly arrested in Hjulsta, a working-class neighborhood of Stockholm, but police refused to confirm a link with the attack.
Six of those injured in the attack were able to leave hospital, while eight adults and one child remained hospitalized, local authorities in the capital said early Saturday.
aw/jm (AFP, Reuters, dpa),dw.com/en