On the night between Sunday and Monday, one person was shot dead and another man was seriously injured in Hjulsta.
The police theory is that the people who were shot have connections to the criminal network "the Filterless" and that the people were looking for people from a rival gang when the attack took place.
Eight are requested to be detained
Six of the people are suspected of murder, attempted murder and aggravated weapon crime.
The two other people who were detained on suspicion of attempted murder.
Two of the total of eight are also suspected of an earlier murder in May this year which is still unsolved.
Connections to Denmark
Several of the murder suspects can be linked to a criminal gang called the Death Patrol and one of the detainees is a resident of Denmark.
It was recently reported in the Danish media that the Death Patrol had allied itself with a gang in Denmark.
SVT has sought chamber prosecutor Carl Mellberg, who is leading the preliminary investigation for a comment.