A man is in critical condition after being attacked by a shark in the Gulf of Mexico

(CNN) – A man is in critical condition after a shark attacked him and partially severed his leg when he fell over the side of a fishing boat in the Gulf of Mexico.

The Coast Guard said a medical helicopter transported the 64-year-old man to a hospital early Friday morning after the attack that occurred 35 miles from Grand Isle, Louisiana.

“The man had reportedly been untangling fishing nets from the ship’s propeller when he fell overboard and was bitten by a shark of unknown size and species,” the Coast Guard said in a press release.

The helicopter removes the injured man from the fishing boat.

“The crew members aboard the Moon Glow (the fishing boat) applied a tourniquet to the partially amputated leg of the man and called for help over the radio.”

When the Coast Guard received the first radio call at 12:51 a.m., a surgeon recommended a medical evacuation by helicopter.

“When the helicopter crew arrived, a Coast Guard rescue swimmer performed first aid on him and applied a new tourniquet to the man’s leg,” the Coast Guard said in the news release. “The crew picked up the wounded man and transferred him to the New Orleans University Medical Center in critical condition.”