ANTIOCH, Calif.—A shooting broke out at a birthday party crashed by uninvited guests, leaving an 18-year-old woman dead and six wounded in Northern California, police said.

The shooting happened early Sunday during a birthday party for a 19-year-old man at a home in Antioch, about 45 miles (72 kilometers) northeast of San Francisco, the Antioch Police Department said in a statement. Those responsible for the violence fled before officers arrived and no one was arrested, police said.

Some of the victims drove themselves to local hospitals after “a panic where attendees … fled in multiple directions and into the neighborhood,” according to police, who noted that they responded to multiple 911 calls about the shooting just before 1 a.m.

The 18-year-old woman was taken to a hospital, where she died. Wounded guests included four other women, ages 19 and 20, and two men, age 18 and 19, police said. Their injuries were not life-threatening.