DOWNEY, Calif. (AP) — Three men were killed in a weekend shooting near a homeless encampment in Southern California, authorities said.

Officers responded shortly before 9 p.m. Saturday to reports of gunfire at a dry riverbed near Interstate 105 in Downey, police said in a statement.

They found three men suffering from gunshot wounds. All three men died at the scene, the statement said.

It’s unclear what sparked the shooting but police said it “appeared to be an isolated incident.”

The incident was under investigation. ABC 7 reported the shooting occurred near a homeless encampment in the city of about 14,000 residents some 25 miles (40 km) southeast of downtown Los Angeles.