Investigators are looking for a car caught in surveillance video driving near the 30-year-old Los Angeles sheriff's deputy who was ambushed and fatally shot in his patrol car over the weekend, authorities said.

Deputy Ryan Clinkunbroomer was shot while on duty at an intersection near the sheriff's station in Palmdale, and was found unconscious by a civilian around 6 p.m. Saturday, according to the Los Angeles County Sheriff's Department.

The deputy was rushed a hospital, where he was pronounced dead, according to Los Angeles County Sheriff Robert Luna.

"This coward or cowards took his life while he's sitting at a red light, waiting to serve our community," Luna said at a Sunday news conference.

It's unknown who opened fire on Clinkunbroomer, or what motivated the attack. But the sheriff said the shooting appears to have been targeted.

Widely circulated video captured a vehicle -- described as a 2006 to 2012 dark gray Toyota Corolla -- driving next to Clinkunbroomer's patrol vehicle, Luna said Sunday.

The sheriff's department on Sunday released photos of the vehicle, calling it a "vehicle of interest."

A law enforcement source told CNN the vehicle is believed to have been used in the shooting.

Luna on Sunday pleaded with the public to come forward if they have video that may have captured the shooting in Palmdale, about 60 miles north of Los Angeles.

"Look at your video and make sure that you didn't capture anything that could be the missing puzzle to apprehending the suspect," Luna said. "I beg you. Somebody has information. Please make things right."

A reward up to $250,000 will be offered for information leading to the arrest and conviction of the person or persons who killed Clinkunbroomer, authorities announced Sunday.

"It's one of the highest ones I've seen," Luna said of the reward. "I'm challenging people's character out there, to find this act absolutely unacceptable and come forward."

The sheriff said Saturday the shooting appears to have been targeted, but cautioned the investigation is in its early stages.

"He was just driving down the street and for no apparent reason -- and we're still looking into the specific reasons -- somebody decided to shoot and murder him. I'm assuming at this point, because he was in uniform," Luna said.

Deputy got engaged 4 days before he was killed

Clinkunbroomer, described as a beloved member of the sheriff's department, had just gotten engaged four days before he was shot and killed, Luna said.

"He was just starting his life," the sheriff said Saturday.

Clinkunbroomer had been with the department for eight years and transferred to the Palmdale sheriff's station in 2018. He was serving as a field training officer.

His father and grandfather both served in the sheriff's department, Luna said.

"Service was running through his veins. He embodied the values of bravery, selflessness and was committed to justice," Luna said in a Facebook post. "Our deputy was a devoted family member and a cherished community member."

Saturday's shooting comes three years after two Los Angeles deputies were shot ambush-style at a train station while sitting in their patrol vehicle. Surveillance video from the incident showed a gunman walking up to the passenger door of their squad car, opening fire and running away.

There have been 83 ambush-style attacks on law enforcement in 2023, resulting in 101 officers shot -- 15 of them fatally, according to a September 5 report from the Fraternal Order of Police.