The fatal shooting of an Oakley man by an Oakley police officer late Saturday night remains under investigation.

Oakley resident James Brennan, 49, was shot once in the head by Officer Ian Jones following a physical confrontation in the 4000 block of Live Oak Avenue. Brennan was taken to Sutter Delta Memorial Hospital, where he was pronounced dead.

The incident occurred just before midnight when Jones saw a car speed past him on Live Oak Avenue. Jones pursued the car and saw it collide with another car. When Jones approached the car, he was attacked by Brennan, according to Oakley Police Chief Chris Thorsen.

"Officer Jones was absolutely in a fight for his life," said Thorsen. "The suspect made multiple attempts to remove Officer Jones' gun, and Officer Jones removed his weapon and discharged one bullet."

Brennan's son James, 27, was arrested at the scene for interfering with a police officer. Brennan's brother Stephen, 46, was also arrested by the Californian Highway Patrol for assault with a deadly weapon when he allegedly tried to run down officers at the scene.

Both were booked into the county jail in Martinez. Brennan's son is out on bail, while the brother was still in custody at press time Wednesday.

Jones, a 12-year veteran with the Contra Costa County Sheriff's Department, is on administrative leave, which is standard procedure after a shooting, according to Thorsen.

Thorsen said it is unclear what prompted the attack by Brennan, or whether he was under the influence of drugs or alcohol at the time.

"The 'whys' of the incident are still under investigation," said Thorsen. "However, the behavior (Brennan) displayed is consistent with what he had displayed in the hours prior to him having contact with Officer Jones. Alcohol, drugs and toxicology reports are still pending."

Jones, who has been a deputy sheriff in Oakley for the past six years, is doing well, said Thorsen. "He's doing better. It's been a tough experience for him, obviously. But what I will say is that every bit of information we have received so far tells us that Officer Jones feared for his life and used lethal force to defend himself, which he is entitled to do pursuant to the law and department policy. He's a good man, and he's got a lot of support, as does his family."