Police say a shark has seriously injured a 20-year-old surfer in an attack off the Australian east coast.

Sam Morgan's left thigh was mauled before sunset Tuesday at East Ballina, 745 kilometers (460 miles) north of Sydney, according to a police statement.

Morgan made his own way to shore, where he was helped by beachgoers. He was flown by helicopter 135 kilometers (85 miles) north to Gold Coast University Hospital.

The attack was the 14th in New South Wales state this year, 11 more than in 2014.

State authorities reported the shark was possibly a bull shark, approximately 2.8 to 3.1 meters (9 to 10 feet) long.