The dog was shot around 6:45 p.m. Tuesday near the Bethel Island Golf Course on 3303 Gateway Road after it charged deputies and bit a police canine, sheriff's office spokesman Jimmy Lee said.
Lee said the pit bull belongs to 29-year-old Bethel Island resident Brian Vorum, who was allegedly threatening to fight people and damaging public property near the golf course.
The dog charged deputies as they tried to make contact with Vorum, prompting deputies to pepper spray the pit bull.
The animal ran away but returned shortly afterward and bit a police canine as Vorum fought with deputies, Lee said.
He said the police canine's handler pulled his dog away and shot the pit bull near its shoulder.
The dog received emergency treatment from a nearby veterinarian and this morning was handed over to Contra Costa Animal Services in Martinez, which is investigating the incident, Lee said.
Vorum, a parolee, was arrested and booked into the Martinez Detention Facility on suspicion of violating his parole and resisting arrest.