At least one person was killed and two others were wounded in a shooting at a California detox center early Monday, police said.

Authorities received a call about a shooting at the Helen Vine Detox Center in San Rafael at about 1:33 a.m., Sgt. Michael Brovelli, from the Marin County Sheriff’s Office, said, according to KTVU-TV. He said responding deputies found three victims – two men and a woman.

The shooting victims were only identified as staff members of the detox center.

One of the injured men died and the two others were transported to a hospital, Brovelli said. The conditions of the wounded weren’t immediately known.

A manhunt was on for the gunman.

The identity of the gunman was not released.