When police officers first go through the training academy, they’re taught that “There’s no such thing as a routine traffic stop.” And this video above, from the Los Angeles Police Department, serves as a good reminder of why officers approach cars cautiously, and how seemingly innocuous interactions with the public can turn violent without warning.

The shooting happened in the North Hills neighborhood of Los Angeles on July 27, about 10:15 p.m. A female officer, whose name has not been released, approached the car and spoke to a driver she knew from previous encounters. She asked him if he was still on probation, and the driver replied that he had nine months left, the video shows. The officer was wearing a body cam, as was her partner, who stood on the passenger side of the car. An in-car camera was also rolling.

The driver, 32-year-old convicted felon Richard Mendoza, appeared perfectly cooperative and kept his hands high and visible while he remained behind the wheel. The video shows no indication that anything is amiss. But as Mendoza climbed out of the car, he quickly drew a .380-caliber pistol from his pants pocket and fired point blank into the officer’s leg, the video shows. He then turned and began firing at the other officer, identified by Los Angeles police as Miguel Alarcon. Alarcon returned fire and killed Mendoza, police said.

“Statistically, the two most dangerous things a police officer can do,” said Jim Pasco, executive director of the Fraternal Order of Police, “is respond to a domestic violence complaint and make a traffic stop. Those are far and away the most dangerous things a police officer does. Pasco said the video demonstrated that “an officer working a stop, regardless of how routine it might seem to an observer, is going to be in a heightened state of alert and the adrenalin’s going to be running.” Alarcon’s nearly instantaneous response to Mendoza’s aggression showed he was ready.

Los Angeles police declined to answer questions from The Washington Post. New L.A. Police Chief Michel Moore told the Los Angeles Times that the wounded officer suffered a shattered femur in the shooting, “I spoke with her, she is okay. … By the grace of God she is alive. Officers are fearful in these situations and the public here gets to see why.” Moore said the officer had worked in the gang unit and was aware of Mendoza’s history. He had prior convictions for selling narcotics and possession of a firearm by a felon.

The LAPD released the video under a new policy requiring body- and in-car camera footage to be made public within 45 days of a shooting by a police officer.

FBI statistics show that at least 50,000 police officers were assaulted in 2015, and 2,000 officers were shot. But those numbers are low because they were submitted voluntarily by police agencies, and fewer than 12,000 of the 18,000 agencies in the United States provided their data. There is no law or rule requiring police to track and submit such statistics. The FBI estimated that the agencies who did provide information covered about 75 percent of the U.S. population.