A teenager was seriously injured in a shark attack off a beach in southern California on Saturday.

The attack occurred around 7am at Beacon’s Beach in the Leucadia area of Encinitas, a city north of San Diego. The Encinitas lifeguard captain Larry Giles said the 13-year-old boy suffered traumatic injuries, but he described it as a nonfatal attack.

The victim was hauled aboard a kayak by three other people who were in the water on opening day of the spiny lobster season, which began at 6am. Giles said the rescuers included an off-duty police officer.

One of the rescuers, Chad Hammel, told a local TV station he heard screaming and realized the boy was yelling: “I got bit!”

Footage of the aftermath of the attack.

The rescuers applied pressure to the boy’s wounds while beachgoers called paramedics. The boy was brought ashore and flown by helicopter to a trauma center.

Witnesses estimated the shark was about 11ft long. Giles said the species had not been determined.

The attack came two weeks after a 26-year-old man died after being bitten by a shark off Newcomb Hollow beach on Cape Cod, Massachusetts.