VISTA -- San Diego police Officer Frank White testified Tuesday about the mounting fear he felt as an "enraged" driver used her car to threaten him during a road-rage clash that left him "terrified" to the point he had to shoot the woman.

"When this person looked at me, I just saw the rage and determination, and just out of their mind," White testified during his felony criminal trial for shooting the woman on March 15, 2008.

"I thought, 'If this person gets a chance to kill me, they are gonna kill me.' "

On cross-examination, the officer -- who was off-duty, out of uniform and in his personal car with his wife during the shooting -- said he pulled his gun, in part, to scare off the woman, Rachel Silva. He did not pull out his police badge, he said, because it was in his back pocket and difficult to reach.

"There was a lot of things to consider," White replied, when the prosecutor asked why he didn't show the woman his badge. "It happened really fast."

White's testimony, coming Tuesday during his trial in a Vista courtroom, marked the first time the 29-year-old officer has publically told his side of the story since shooting Silva and her 8-year-old son during the road-rage clash in an Oceanside parking lot.

White said Silva -- so enraged during the encounter that veins were "popped out of her neck," he said -- used her car "as a deadly weapon" against him, leaving him "scared."

He said he was defending himself and his wife against Silva's "aggressive, assaultive behavior."

He spent nearly five hours on the witness stand and will return to it again Wednesday morning to finish his testimony.

The officer has been charged with negligently firing a gun -- a felony -- along with a misdemeanor charge of brandishing the weapon.

White, who faces up to nine years in prison if convicted, is the first peace officer charged in San Diego County in more than a decade for firing at a perceived aggressor.

In front of a full courtroom, White's voice mostly stayed firm as he told the jury of nine women and three men details of his account, from the time Silva started to follow him after a perceived driving slight, to the time he fired his weapon just after 9 p.m. on a Saturday.

Silva, he said, began tailgating, revving her engine, screeching her tires and screaming at him. He said he drove slowly through the parking lot hoping that Silva, a stranger to him, would feel that she made her point and give up the chase. She did not -- so he told his wife to call 911.

He said his mind raced with possibilities as to who this woman was and why she was chasing him. Perhaps, he said, it was a case of mistaken identity. Perhaps it was road rage. Perhaps it was someone he'd previously arrested who had held a grudge.

According to testimony, Silva blocked White's car and then clipped it with hers during the bizarre slow-speed pursuit in front of a Lowe's home improvement store.

White said he pointed his gun at her, shouted to her that he was a police officer and ordered her to stop.

"I didn't see any reaction," White said of Silva. "It indicated to me that she was so angry, she didn't care that I had a gun."

It is unclear if Silva saw the gun at that point. She has not made any official statements that have been made public. And her young son testified last week that seconds before the shooting, he saw the gun -- and screamed at his mom to tell her.

White said he tried to get out of his car, but didn't get a chance to for fear he could have been crushed as Silva quickly backed up, positioning her car parallel alongside his door, within inches of him.

Her car scraped against his -- and that, he said, is when he started shooting, emptying his five-shot revolver into Silva's car.

White, who has two young sons, said he had not seen Silva's boy in the front seat. Learning that he had shot the third-grader, he said, left him "devastated."

"I had no idea there was a child in the car," White said, his voice cracking slightly. "As a parent, I can't even imagine someone putting a kid in that situation."

White paused, took two deep breaths, and then continued.

"I just, if I had seen the kid," he said, "I think I would have let my leg get taken off before I shot into that car."

On cross-examination, the prosecutor, Deputy District Attorney Jeff Dusek, repeatedly asked White why he had not tried to diffuse the situation without using his gun.

"None of it was working: the turning, the driving, me trying not to provoke her," White said. "I felt like it was escalating, so I pulled out my gun."

White said he pulled out his gun for two reasons: to either detain Silva until uniformed officers arrived or to make her go away.

"You wanted to scare her so she would leave?" Dusek asked.

"I wanted her to stop," White replied.

"And leave?" Dusek asked.

"That would have been good," White answered.

White said he identified himself to Silva by shouting commands such as "Police! Stop!"

He said he threw his car into reverse, so he would have room to open his door and get out of the car. And that, he said, is when Silva backed up her silver Honda, side-swiping his Mercury Milan.

White fired his gun, shattering the glass of his rolled-up driver's side window.

"I remember shooting at the car as it is hitting me," he said, later adding that he was shocked when he eventually saw the damage to the two cars wasn't much more severe than scrapes and dings and a broken mirror casing on Silva's car.

Silva has invoked her legal right against self-incrimination and thus is not expected to testify. For her role in the confrontation, she has pleaded guilty to felony child endangerment and misdemeanor drunken driving. Blood tests showed Silva was legally too drunk to drive at the time of the incident, and she had marijuana and methamphetamine in her system.

State prosecutors declined to charge her with assault with a deadly weapon for her use of the car in the incident.

Silva faces up to four years in prison when she is sentenced in July.

Call staff writer Teri Figueroa at 760-740-5442.