Three people were found dead Sunday at a Marin County home in what the sheriff’s office is investigating as a suspected double murder-suicide.

Investigators’ preliminary findings indicate that Kevin Mannix, 68, a retired San Francisco police sergeant, fatally shot his estranged wife, retired San Francisco police Deputy Chief Ann Mannix, 65, and their adult daughter, Katherine Elizabeth Mannix, 24, before killing himself, authorities said.

The Marin County Sheriff’s Office received multiple reports of gunfire at 5:03 p.m. at the family’s home on Strawberry Circle in Strawberry, an unincorporated community east of Mill Valley. Deputies arrived within minutes, contacted a person who had escaped the home and secured the area before entering. They found three people dead inside.