The police have not yet arrested any suspects.
The 18-year-old who was shot is also not previously known to the police.
In the clip above, the police tell how they proceed with the investigation.
Several shootings in a short time
The shooting is one in a series of serious shootings in Södertälje.
Most recently in June, a 20-year-old man was shot to death in the Blombacka district and in April a man was shot in the cemetery and who was later found dead in a villa garden next door.
At the end of February, a man was found shot dead in a car in Ronna and it is the only investigation so far that has a suspect.
- These are difficult crimes to investigate and we need to get witness information about what happened.
Many times you do not go to the police and tell what you know, says Kristoffer Olofsson.