Police in Venice Beach, California are hunting a man who knocked out a woman with a single coward punch.
The attack was caught on security camera, as was an argument the pair had shortly beforehand in a grocery store.
They'd met earlier on Sunday at a festival, where police say they had a disagreement.
That evening they ran into each other at a grocery store, and began to argue. Things escalated as another woman tried to get between them.
Outside the store, the woman can be seen following her future attacker. It's not clear from the video if either of them are saying anything.
Then seemingly without warning, the man spins around and coward punches the woman in the face, and she collapses.
He begins to walk away, and glances back at his victim. A passerby grabs the opportunity to put the thug in a headlock, and other members of the public rush in to stop him escaping, but he shakes them off and makes a getaway.
"I'm not really surprised, because stuff like this happens all the time around here," local woman Erinn Williams told CBS News.
"I think people were drinking and getting riled up."
Police are trying to identify the attacker. It's not clear whether he's a local or from out of town.
"She confronted him on his way out," Sgt John Marquez of the LAPD told the Los Angeles Times.
"He just turned around and punched her out. She pretty much doesn't remember."
Coward punches, or "king-hits" as they're also known, have been a problem on this side of the world too.
Last month police released video of two one-punch assaults that took place in the Auckland CBD within minutes of each other.
Ex-pro boxer Mike Angove has called for one-punch killers to face murder, rather than manslaughter charges.
CBS / Newshub.