BRENTWOOD, Calif. (KRON) — One was killed and three injured at a shooting early Thursday outside a Brentwood 24 Hour Fitness, police confirmed to KRON4.

There is a major law enforcement presence at and outside the gym, located at 5961 Lone Tree Way, and police are telling people to avoid the area.

“BPD officers are currently working an active investigation at the 24 Hour Fitness on Lone Tree Way.,” the statement, posted to Facebook, reads. “Please avoid the area as the gym and parking lot will be closed for several hours.” Police continued that there is not currently a threat to public safety.

The shooting was just before 2 a.m., beginning with an argument on or near the basketball court. The confrontation went to the parking lot, where it escalated. One person was killed and three transported themselves to hospitals with injuries, according to police.

At least two people grabbed their guns and started shooting, based on surveillance footage. At least one of the injured people is believed by police to be a minor.

Two suspects have been detained in relation to the incident.

This is a developing story. Check back for updates.