A surfer was seriously injured Saturday in a great white shark attack about 20 miles south of San Francisco.
The 39-year-old victim was in the water Saturday morning at Gray Whale Cove State Beach in San Mateo County when the shark attacked him, the sheriff's office said.
"He was out surfing and a great white came up and just took one bite out of him and released him," Brian Ham of the California Department of Forestry and Fire Protection told NBC Bay Area.
The station reported the surfer was bitten in the back of his right thigh.
He "was treated with advanced life support measures" at the scene, Cal Fire tweeted.
Thomas Masotta said he was fishing on the shoreline when he spotted the wetsuit-clad victim emerge from the water and walk toward him.
"He called out to me, then collapsed," Masotta said by email. "He was rolling around on the ground and said he wasn’t in a lot of pain but was worried that he was losing a lot of blood."
The witness said he tried to call 911 but had difficulties reaching operators because the beach is on a relatively remote stretch of coastline.
"So we tied off his wound with straps from my backpack and elevated his leg," Masotta continued. "Then I ran up to the road and was able to make another call to 911."
The victim was taken to San Francisco General Hospital's trauma facility, where he was stabilized in serious condition, authorities told NBC Bay Area.
Sheriff's officials described the shark as measuring 6 to 8 feet. The beach was subsequently closed.
This article was originally published on NBCNews.com.