IMPERIAL BEACH, Calif. - A shark warning was in effect for a Southern California beach Thursday after a group of surfers spotted a great white just off the coast, CBS affiliate KFMB-TV in San Diego reports.
The surfers in Imperial Beach saw some dolphins scatter Tuesday morning, and then the shark's dorsal fin appeared, lifeguard Capt. Robert Stabenow said.
Photographer Jeff Wallis was taking pictures when he captured the image.
City News Service says the shark is estimated to be 16 to 18 feet long. Imperial Beach is south of San Diego.
An Imperial Beach lifeguard saw the image online Tuesday and alerted his colleagues, who tracked down the photographer and interviewed him.
The nonprofit Shark Research Committee and Scripps Institution of Oceanography looked at the picture and confirmed that the fin appeared to be from a great white.
Stabenow said great white sightings in the area are "very rare."
"We hope most of the community heeds the warning and stays out of the ocean for the next few days," he said.
Stabenow said the number of surfers Thursday morning appeared down slightly, though dozens were bobbing on their boards in the same general area.
Unless the shark is seen again, the warning will expire Friday, Stabenow said.
Great whites, which can grow up to about 20 feet, mainly subsist on sea lions and other sea mammals.