As the FBI joined a massive search for a gunman who ambushed two deputies, Los Angeles County Sheriff Alex Villanueva said he’s worried about more attacks on law enforcement officers and is warning members of his agency to watch each other’s back.

The two deputies, both shot multiple times as they sat in their patrol vehicle Saturday night, were listed in stable condition on Monday in a Los Angeles hospital after undergoing surgery, officials told ABC News.

The search for the gunman went into its third day Monday and Villanueva told ABC News that he has sheriff’s deputies on heightened alert for a repeat attack.

“This is going to cause us to be a lot more concerned about when we approach vehicles when we’re out there on the streets,” Villanueva said. “We have everybody paired up in two-man vehicles now. So, we’re going to have to be watching out for each other’s back out there on the streets.”

Villanueva said his department is using all the resources it can muster in the search for the gunman, emphasizing the urgency to identify the dangerous suspect and get him off the streets before he’s able to strike again.

The FBI announced it is lending resources to the manhunt and “stands ready to assist in response” to the attack. The Los Angeles County Board of Supervisors on Sunday authorized a $100,000 reward for information leading to the arrest and conviction of the gunman.

The shooting unfolded about 7 p.m. local time on Saturday as the sheriff’s deputies sat in their marked patrol vehicle near the Martin Luther King Jr. Transit Center in Compton, authorities said. Surveillance video released by the sheriff’s department showed an individual dressed in black shorts, a dark jacket and wielding a pistol walk up to the patrol vehicle and open fire without warning through the passenger-side window.

The shooter, who authorities said is believed to be Black and 28 to 30 years old, ran to a black four-door sedan and sped away, authorities said. As the gunman fled, the surveillance video showed the patrol vehicle’s passenger-side door open and one of the wounded deputies, described as a 31-year-old mother of a 6-year-old child, stumble out.

Villanueva told ABC News that despite being shot four or five times, including once in the jaw, the female deputy walked around the patrol vehicle to help her 24-year-old partner, who suffered gunshot wounds to his forehead, arms and a hand.

“She goes around the car, applies a tourniquet to him to stop the bleeding. She gets on the radio and she’s calling for help and she’s having a hard time because she can’t speak very well,” Villanueva said.

In a recording of the female deputy’s desperate radio call for assistance, she is heard saying, “I’ve been shot. Send help.”

The wounded officers were rushed to St. Francis Medical Center, both initially in critical condition, and immediately underwent surgery, officials said.

Gov. Gavin Newsom condemned the ambush as a “cowardly, horrific act” and offered prayers for the recovering deputies.

During a campaign rally in Nevada Sunday night, President Donald Trump said his thoughts are with the wounded sheriff’s deputies, “who were fighting for their lives when a vicious criminal walked up to their vehicle and shot them at point-blank range.”

Protesters quickly gathered outside Francis Medical Center following the shooting, some heckling deputies congregating near the emergency room entrance. One protester who livestreamed the event shouted expletives at the deputies, saying, “I hope they f—— die.”

Josie Huang, a news correspondent for the Southern California Public Radio station KPCC/LAist, was detained by sheriff’s deputies while at the hospital reporting on the ambush shooting and trying to document the arrest of a protester.

In a series of Twitter posts, Huang wrote, “I was filming an arrest when suddenly deputies shout ‘back up.’ Within seconds, I was getting shoved around. There was nowhere to back up.”

Sheriff’s officials allege that Huang was taken into custody on suspicion of obstruction of justice and “interfering with a lawful arrest.” A sheriff’s department spokesman said Haung did not have proper credentials identifying herself as a journalist.

Huang disputed the statement, saying her press credentials were hanging around her neck. She said her camera continued to record after she was forced to the ground. She said that on the footage she can be heard repeatedly identifying herself as a reporter, shouting “KPCC” and yelling, “You’re hurting me.” Huang was taken to the women’s jail at the Century Regional Detention Center and released about 4 a.m. on Sunday.

“These are challenging and stressful times for everyone, but Josie Huang was arrested while doing her job. The charges should be dropped,” KPCC said in a statement. “Her arrest is the latest in a series of troubling interactions between our reporters and some local law enforcement officers. Journalists provide an essential service, providing fair, accurate and timely journalism and without them, our democracy is at risk.”

Tensions have been running high in the area and protests have occurred nearly every night outside the South Los Angeles Sheriff’s Department substation since the Aug. 30 death of Dijon Kizzee, a 29-year-old Black man who was fatally shot by two sheriff’s deputies.

Deputies pursued Kizzee for allegedly riding a bicycle in violation of vehicle laws, authorities said. Following an altercation with the two deputies, Kizzee allegedly dropped a gun and was shot multiple times, officials said.

Kizzee’s family has called for the deputies involved in the shooting to be identified and prosecuted.