The sharks were spotted off the coast of Southern California where paddlers were warned YouTube

Paddle-boarders in Orange County got the shock of their lives on Wednesday (11 May) when they heard a helicopter announcement that nearby were a group of great white sharks.

The school of sharks was swimming near people in the water at Dana Point, leading to Deputy Brian Stockbridge announcing over the helicopter loudspeaker to "exit the water in a calm manner. The sharks are as close as the surf line."

There have been a number of shark sightings this week and warnings have been posted up beaches around Southern California, including at San Onofre State Beach, where a woman was bitten by a shark on 29 April.

The Los Angeles Times reports that shark activity has been put down to "thriving aquatic ecosystem" in the area and that 10 to 20 juvenile sharks regularly swim near Long Beach.

Fire captain Cameron Abel, of the Marine Safety Unit in Long Beach, said that the sharks were around most of last summer.

"We'd spot them periodically and toward the end of the summer, they disappeared," he said.

Only days previously, more than a dozen great white sharks were captured on an underwater camera off the coast of California. The sharks were spotted in Long Beach by towboat captains Ricky Birks and Mike Del Grande, who were towing broken-down vessels in the area.

The school of sharks were spotted off the coast of Orange County Orange County Sheriff's Department, via YouTube