California authorities are trying to determine why a Central Coast man stabbed and beat his sister, mother and a third person to death in their home.

The Santa Barbara County Sheriff's Office said 43-year-old David Gerald McNabb was shot to death in a confrontation Friday night when deputies entered the home in the town of Orcutt.

McNabb had been a sheriff's custody deputy from July 2001 until he resigned in March 2012. His record included a September 2012 arrest in neighboring Ventura County and a 2014 conviction for felony domestic violence, the office said.

The victims were identified as his sister, 34-year-old Nicole McNabb; his mother, 64-year-old Melanie McNabb; and 63-year-old Carlos Echavarria. All lived at the scene.

A Sheriff's Office statement said the county dispatch center received a call at 8:05 p.m. from a person who entered her home and found a bloody scene inside.

"She discovered a victim covered in blood in a bathtub, fled the residence and called for help," it said without identifying that person.

Responding deputies entered the home, contacted the suspect and determined he was armed with a rifle, the statement said.

Emergency notifications were sent to the neighborhood telling people to shelter in place, and the sheriff's special tactical unit and hostage negotiators were summoned.

Deputies learned there were additional people inside and made further entry into the residence.

"They made contact with the armed suspect, a confrontation ensued during which the suspect was initially shot with less lethal munitions, followed by the use of deadly force," the statement said. "The suspect was transported to a hospital by ambulance and was subsequently pronounced dead."

The three victims were found inside the home.

Orcutt is about 150 miles (241 kilometers) northwest of downtown Los Angeles.