An Uzbek man being held in custody is the suspected driver of a hijacked beer delivery truck that ploughed into crowds in central Stockholm, killing four people and wounding 15 in an apparent terror attack, police say.
The man, 39, previously known to Swedish intelligence services as a marginal figure with no clear links to extremist groups, is suspected of mowing down pedestrians and smashing through a store front on Friday.
"Nothing indicates that we have the wrong person, on the contrary, suspicions have strengthened as the investigation has progressed," Dan Eliasson, head of Sweden's national police, told a news conference on Saturday.
The man, detained on Friday night on terrorism charges after the attack in the capital, appeared to have acted alone but "we still cannot rule out that more people are involved", he said.
The suspect, from the central Asian republic of Uzbekistan, will be represented by a court-appointed lawyer.
Eliasson said there were "clear similarities" to an attack last month in London.
Vehicles have also been used as weapons in Nice and Berlin in the past year in attacks claimed by Islamic State.
There was no immediate claim of responsibility for the attack in Sweden.
Police said they had found a suspicious device in the vehicle, which ended up rammed into the Ahlens department store, but said they did not yet know if it was a homemade bomb.
Local authorities in Stockholm said 10 people including a child were still being treated in hospital, with two adults in intensive care.
Sweden will hold a minute's silence at midday on Monday to mourn the dead.
A gaping hole in the wall of the store showed the force of the impact from the truck, which was removed overnight for examination by forensics experts, and dozens of people gathered to pay their respects and leave flowers, stunned by the attack.
Crown Princess Victoria was among them, laying a bouquet of red roses. "I feel an enormous sadness, I feel empty," she said, urging Swedes to unite in their grief.
Prime Minister Stefan Lofven also visited the site and struck a defiant tone: "All of us feel anger over what has happened, I also feel the same anger, but we also need to use that anger for something constructive and go forward."