It was at around 8 pm on Monday that the block hit the car, which was damaged in connection with the collision.
The driver survived without physical injuries.
Where the block came from is not known, but according to the police, it is likely that someone threw it from a bridge.
- We have patrols on site that check if it may be that the block has come loose from a bridge.
So far, we have not found any bridge that is missing a part, says police spokeswoman Carina Skagerlind.
The case is classified as attempted aggravated assault.
No suspect has been arrested.