At 22.30 on Saturday evening, there was an alarm that two cars had collided on Norrköpingsvägen south of Brickebacken. According to witnesses, one of the cars drove over on the wrong side of the road.
The driver of the car believed to have caused the accident has been taken to hospital. The injuries are considered to be minor.
The driver was arrested at the hospital and is suspected of causing the death of another and gross negligence in traffic.
Three people were in the oncoming car and the driver and a passenger died in the crash. The third was taken to hospital with serious injuries.