The woman, in her 25s, was shot dead at a bathing spot in the area on Friday night.
Witnesses heard several shots.
A man has been arrested on suspicion of murder.
- I felt nauseous when I found out what happened.
I did not think such a thing could happen here, says an anonymous witness to SVT Nyheter Norrbotten.
The police state that intensive investigative work is in progress.
A man in his 30s has been arrested.
Hear the witnesses in the video above.