A riot broke out on Sunday in downtown Huntington Beach, California after Vans U.S. Open of Surfing contest. The New York Daily News.

It's not clear what started the riots but witnesses say according to the Daily News that fights started breakout out after 7 p.m. as a crowd was on their way from the beach.

"We were all huddled inside the building and we had the lights off because all the people were up here mobbing around, and I was inside and I saw them tearing down the stop sign," Burt Etheredge, an employee at a bike shop, told NBC. "As soon as that stop sign came down, I knew that stop sign was coming through the window. And sure enough, two seconds later, it did."

"I heard shots going off, and the whole crowd just started running," witness Russ Mundi told the L.A. Times.

The Easyrider bike shop was a target of the rioting as crowds tore down a stop sign and used it to ram through the glass storefront. Ryan Hartzog a store manager said he arrived earlier that evening after an employee said there had been issues from the crowd who were at the surfing contest.

"The employees stayed in the shop, keeping the doors locked and the lights off, but then armed themselves with wrenches and bike seat posts when they saw people outside pull down a stop sign, Hartzog said.

He said rioters used the sign to smash through the window, stole one bike and tried to tried to take a second. Employees managed to hang onto the second bike in a tug-of-war with a looter," reported The LA Times.

Hartzong said to the LA Times, "It was a little intense. Who knows what could have happened?"

14-year-old Dominic Coffey, said to the LA Times, "Usually at the U.S. Open, people throw their trash everywhere, but I've never seen it get this wild."