A 16-year-old boy surfing at “Dead Trees” surfing spot at Pohiki on Hawaii Island was attacked by a shark Sunday afternoon, county fire officials said.

The teenager sustained multiple cuts and puncture wounds to his legs and was transported by ambulance to the Pahoa Fire Station before boarding a helicopter bound for the Hilo Medical Center Emergency Room, the Hawaii County Fire Department said.

He was apparently attacked from behind by a grey shark about eight feet long.

Firefighters arrived at the Pohoiki Boat Ramp just before 2 p.m. to find lifeguards already treating the boy.

A fire department helicopter surveyed the area around the attack but could not locate the shark, officials said.