A man in his 40s was seriously injured when a boat’s propeller cut him in waters between Mahukona and Kapaa Park, the Hawaii County Fire Department said.

The man was swimming with a friend about 11 a.m. Monday when a boat hit him and knocked him unconscious, the fire department said.

People in the boat pulled the injured man aboard and headed back to Mahukona Pier. The man was barely breathing, with lacerations from the boat’s propeller to his head, shouders and arms, the fire department said.

The fire department got the call at 11:10 a.m. A department helicopter flew the swimmer to North Hawaii Hospital.