Earlier this week, a California resident was driving down the 10 Freeway, near La Brea Avenue, when he noticed something truly shocking: a California Highway Patrol officer repeatedly punching a black woman he had pinned down.

Unfortunately for the CHP, most drivers nowadays have cellphones with recording devices: the whole incident was caught on camera, uploaded onto YouTube, and sent to various press agencies.

Fair warning: the video is hard to watch. It shows a woman being caught and held down on the ground along the side of the freeway, while a large officer punches her,repeatedly, in the face. She appears to try holding up her hands to shield herself. It was filmed by a passing driver, David Diaz, early Tuesday evening, in L.A.

According to the AP, Diaz got to the scene as the woman was walking off the road, only turning around when the officer yelled at her.

“He just pounded her,” Diaz said to CBS Los Angeles. “If you look at the video, there are 15 hits. To the head, and not just simple jabs. These are blows to the head. Blows. Really serious blows. And this is ridiculous to me.”

“He agitated the situation more than helped it,” he added.

In response, the CHP has said it’ll investigate the incident, though they were quick to point out that it would be “premature” to conclude anything without knowing the full context. (Though what could merit bashing a woman’s face over ten times has been left up to the public’s imagination.) In the meantime, at least, the punch-happy officer has been put on administrative leave. Said the CHP in a statement on Thursday:

The California Highway Patrol (CHP) is aware of the video and we are looking into the incident. As a matter of policy, every time there is a use of force by our officers, there is a review conducted to determine whether the use of force was appropriate. That will be done in this case, however, since there is an ongoing investigation, it would be premature to comment on this specific video segment without reviewing the entire incident.

According to CHP Assistant Chief Chris O’Quinn, the officer in question was simply responding to a report of a woman roaming on the freeway; when he got to her, she was making her way down an off-ramp and wandering between lanes. The woman, who remains unidentified, is unharmed — they say — but undergoing a psychiatric evaluation.

Of course, this is far from the first incident of police brutality to take place in the U.S., and not even the first to be caught on film. Some police forces are more extreme than others — the Albuquerque police, for example, have a “pattern of use of excessive force, including deadly force,” according to the DOJ — but individual cases of police violence are far from rare. In fact, according to the Center for Research on Globalization, ”500 innocent Americans are murdered by police every year (USDOJ).”

Just a quick look at Tuesday’s video, or the responses to the New York Police Department’s misguided Twitter campaign (#MyNYPD), brings that reality painfully home.