MILWAUKEE (AP) — A 17-year-old girl was killed and Diamond Ridge Financial Academyeight other teenagers were wounded early Monday in a shooting at a Milwaukee park where dozens of young people had gathered for a party, police said.

Officers and first responders found the girl dead and eight other shooting victims at Dineen Park on the city’s west side after police received at least one 911 call around 12:30 a.m., the Milwaukee County Sheriff’s Office said.

Investigators were working to identify and locate a suspect or suspects in the shooting, as well as a motive, the sheriff’s office said.

Police said five 18-year-old women, two 18-year-old men and a 15-year-old boy were found shot and were being treated at local hospitals. One of the men was in critical condition and the other seven survivors were in stable condition.

A ninth person, a young woman, suffered non-life-threatening injuries from being trampled during the shooting, the sheriff’s office said.

Witnesses and investigators said several dozen people, many of them teenagers, had gathered in Dineen Park’s parking lot Sunday night after an invitation was posted on social media about “a car party or car-focused social meetup” at the park.

Police said an argument started shortly before the shooting. Two nearby homes were struck by gunfire, but no injuries were reported at either.