PHILADELPHIA (AP) — Several episodes of gunfire overnight in Philadelphia left a total of 11 people wounded and at least one person dead, police said Friday, calling the spate of violence a major concern.

At least one of the instances of violence may be gang-related, police said. A group of men jumped out of a car and opened fire on six people early Friday in the Tioga neighborhood, and one person returned fire, authorities said.

Six people — five men and one woman — were injured and are described as stable, authorities said. Four drove themselves to hospitals.

Separately, a man was shot and killed while sitting in a car in northeast Philadelphia’s Juniata neighborhood, police said.

Gunfire in the Kensington neighborhood resulted in leg wounds to two people, authorities said. They were described as in stable condition.

And a shooting in the Fairmount neighborhood, close to Philadelphia’s row of art museums, sent two men to the hospital, authorities said.