Censor.NET reports citing The Telegraph.
Some reports suggested he had previously posted jihadist propaganda on his Facebook page and had images of people injured in the explosion at the Boston Marathon in April 2013.
Swedish media claim the man has already confessed to his involvement.
On April 7, a truck ploughed into people on one of the Stockholm sidewalks and ran into building a few moments after. The incident occurred on popular pedestrian street Drottninggatan. The available photos of the scene posted on social media show that the truck's cabin caught fire.
At least four people were killed and another 15 were injured, including children. Nine of the injured are in a serious condition.