Gunfire erupted following a fight in Detroit overnight, leaving three men dead and three other people wounded, police said.
The shootings happened after two women were fighting outside a home and one of them returned with a man. Shots were then fired, hitting six people, police said.
The victims ranged in age from 17 to 45.
Two were admitted to hospital in a critical condition.
A man who was shot in the chest and a woman shot in the knee appeared to be innocent bystanders who were at or near their homes.
Others wounded included a 17-year-old girl who went to a hospital on her own with a bullet wound to a hand. The injury was not considered life-threatening.
Police did not release information about a suspect, and said they did not know whether all those killed were involved in the fight.
“We feel that some of these people knew each other and the suspect will be apprehended,” a spokesman added.
The shootings came less than a week after gunshots during a fireworks display in Detroit wounded nine people.