LOMPOC, Calif. -- The beaches near Lompoc where a man was fatally bitten by a shark this week remained closed Thursday in what authorities described as a safety precaution to clear the waters of potential hazards.

Francisco Javier Solorio Jr., a 39-year-old Orcutt resident, died at Surf Beach on Tuesday of a massive wound to the torso after being bitten by a great white shark, estimated at 15 to 16 feet in length. The shark left a huge bite mark on Solorio's surfboard.

Ralph S. Collier, an expert from the Shark Research Committee of Chatsworth, determined the great white's size by measuring the distance between the tooth puncture marks on the board.

The beach at Vandenberg Air Force Base was closed off by a locked gate. The 72-hour closure, which began Tuesday at 3:17 p.m., was expected to lift Friday afternoon.

The windy, dune-fringed beach is five miles from Lompoc. Locals say it is a popular spot to hike and walk but that the waters are cold and rough with an undertow. More people go north to Pismo Beach or south to Santa Barbara for swimming and surfing.

"It's Surf Beach and, ironically, we're advising people not to surf it," said Sherwin Gunn, an employee at Surf Connection, a Lompoc shop that offers gear for skateboarders and surfers. Solorio was an avid surfer who had frequented the spot since he was a boy. He is survived by his wife and their young daughter.

The day before Solorio's death, the family of Lucas Ransom, a 19-year-old chemical engineering student at UC Santa Barbara, gathered at Surf Beach in his memory. He was killed by a shark on Oct. 22, 2010. They also paid tribute to Ransom, who would have graduated from the university last June, by establishing a scholarship in his name.