Police say four people, including a young girl, were killed when a car exploded in a roundabout in the Swedish city of Goteborg.

The cause of Friday's explosion was unclear but police said they had started a criminal investigation.

After initially releasing few details, police confirmed Saturday three people were pronounced dead at the scene while the girl was taken to hospital where she died. They didn't the release the ages or identities of the victims or say whether they were related.

Rescuers said the car exploded in a roundabout near a fire station and was destroyed by the time they got there.

Goteborg, Sweden's second-largest city, has seen a surge in violent conflicts between rival criminal gangs, including a restaurant shooting in March that left two people dead.