04/15/2010 05:12 am ET Updated Dec 06, 2017

Mavericks Surf Contest: Waves Sweep Away Spectators (PHOTOS)

(AP) HALF MOON BAY, Calif. — Two huge waves swept away spectators watching a Northern California surfing contest Saturday morning, causing broken bones and other injuries to people standing on a seawall.

Thirteen people were injured, with two immediately transported to area hospitals. Eleven others were being treated at the beach for injuries including "a couple broken legs and broken hands and so forth," according to California Department of Forestry and Fire Protection Battalion Chief Scott Jalbert.

"They're being treated here and if necessary they'll be transported" to hospitals, he said.

He estimated "a couple hundred" people were on the seawall when the waves struck.

Witnesses said the wave knocked out a large scaffold holding speakers broadcasting the Mavericks Surf Contest, held in this tiny harbor town 25 miles south of San Francisco along Highway 1.

"It just came out of nowhere and wiped us all out," said Pamela Massette of Corte Madera. Her left hand and left knee were scraped and bleeding and she was wet from head to toe. She was heading home minutes after arriving.

Brandon Snider also was hurt. He said everyone's concentration was on the contest when a 5-foot to 6-foot wave "wiped out the entire seawall." He said it's unclear how many people were on the seawall, but he believes some were injured seriously.

Snider was getting his knee taped up by a contest volunteer as he spoke to an Associated Press reporter.

Authorities moved bystanders from the sea wall and about 100 yards back from the water, but spectators were still able to watch the surf contest, he said.

"Nobody was swept away into the water. They were just swept onto the beach area pretty hard," Jalbert said. "It's pretty rocky. We've cleared the beach area so this doesn't happen again."

The surfing contest offers a $150,000 purse, making it the most lucrative big-wave contest in the world.

The contest is not held every year and is called only when conditions are prime. Competitors voted to hold the contest because forecasts called for record-breaking tall waves, despite warnings that strong winds could make those breakers dangerously unpredictable.