One California Highway Patrol officer was killed and two were injured on Monday in a gun battle in Riverside, California, a department spokesman said.

A suspect was injured and neutralized, according to NBC Los Angeles.

Police officers returned fire when the suspect shot at them during a traffic stop, said Riverside Police Department spokesman Ryan Railsback.

The incident took place at about 5.35 p.m. local time, and shots were heard as police pulled a fellow officer out of the line of fire, according to NBC Los Angeles.

“One officer was transported to the county hospital in Moreno Valley in our (police) helicopter,” Railsback said. “The other officer was taken to the hospital in a CHP unit.”

According to the affiliate, aerial footage showed that bullet holes had shattered the windshield of an officer’s vehicle. Emergency personnel were seen giving CPR to one person and there were traces of blood on the hood of a white truck, the network reported.

Riverside is located about 35 miles east of Los Angeles. The incident reportedly took place at Eastridge Avenue near the 215 Freeway.

Recent mass shootings in the U.S. have reignited the debate over gun violence. On Aug. 3, a lone gunman opened fire at a Walmart store in El Paso, killing 22 people. Within 24 hours, another mass shooting occurred in Dayton, Ohio, killing at least 9 people.