A shooting at a house on a quiet suburban cul-de-sac left five people dead in what authorities said could be a murder-suicide among relatives.

Police officers responding to a call of shots fired at about 5:20 p.m. Sunday found two men and two women dead at a house on a cul-de-sac, Riverside County sheriff’s Sgt. Dennis Gutierrez said. A fifth victim, a woman, died at a hospital, he said.

Investigators believed one of the victims was also the shooter, Gutierrez said. Officials know the victims are “related in some way,” though not members of a single nuclear family, Gutierrez said.

Two of the victims were found inside the house and the other three on a patio outside, he said.

The men were identified as Jeffrey Blixt, 45, and Matthew Blixt, 17, Gutierrez said. The women were not identified because authorities have not notified relatives.

Temecula is about 50 miles north of San Diego.