Swedish media are reporting that a 39-year-old Uzbekistan national was arrested. Police say the man is "likely" to have carried out the attack.
Swedish police say they have arrested the man suspected of deliberately driving a truck into pedestrians in central Stockholm killing four people on Friday.
When asked whether the man arrested drove the truck, police spokesman Lars Bystrom said, "Yes, it is correct, it is likely him."
Bystrom declined to comment on Swedish media reports that the arrested man was a 39-year-old from Uzbekistan.
Flags are being flown at half-mast in the Swedish capital following the terror attack.
Swedish state television reported on Saturday that police had also found a bag of explosives in the truck.
TRT World spoke to journalist David Landes in Stockholm to get the latest information.
Meanwhile, Stockholm's Karolinska hospital says six of the 15 injured have been released following treatment while eight adults and one child remain in hospital.
Sweden's state prosecutor Hans Ihrman on Saturday said the unidentified suspect should face a pre-trial custody hearing before midday on Tuesday or be released.
The most recent such attack in Stockholm was on December 11, 2010, when an Iraqi-born Swede, Taimour Abdulwahab al-Abdaly, detonated two devices, including one that killed him, in central Stockholm.
TRT World's Christine Pirovolakis reports.