Watch vicious knockout in crowd brawl at Las Vegas boxing event

Fans were throwing hands—and connecting!—at a boxing event Saturday in Las Vegas.

Serhii Bohachuk and Vergil Ortiz Jr. were scheduled to headline an event at Michelob Ultra Arena, but two fans in the audience stole the show after a brief brawl that left one of them unconscious.

In the clip below, two men start throwing hands, an exchange that ends quickly when one lands a right cross that floors the other.

Security can be seen interjecting shortly after the KO and escorting the “victor” from the arena.

According to boxing reporter Francisco A. Salazar, the punch was indeed a knockout blow and the fallen fan was down for some period of time. He was later transported out of the area via wheelchair, with others in the audience applauding.

See Salazar’s report below.

In Saturday’s main event, Bohachuk defends his interim WBC light middleweight title against the undefeated Ortiz.