Swedish police arrested a second man in connection with the truck attack that killed four people in central Stockholm on Friday, Swedish public broadcaster SVT reported. Police said that the first man who was arrested is suspected of being the driver.
According to STV, the second man was arrested in the northern suburb Hjulsta and is said to be connected to the first man, who was detained shortly after the attack in Marsta, just north of Stockholm.
"The person in question has been arrested as the culprit ... in this case the driver," police spokesman Lars Bystrom said, referring to the first detainee.
At least four people were killed and 15 were wounded on Friday after a truck rammed into a crowd on a shopping street and crashed into a department store in central Stockholm, in what the prime minister said appeared to be a terror attack.
There was no immediate claim of responsibility.
"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 Reuters.
The truck had been stolen while making a delivery to a restaurant further up Drottninggatan, Spendrups Brewery spokesman Marten Lyth said. A masked person jumped into the cab, started the truck and drove away.
"Sweden has been attacked. Everything points to the fact that this is a terrorist attack," Prime Minister Stefan Lofven told reporters during a visit in western Sweden before immediately returning to the capital.
DPA contributed to this report.