An Australian surfer’s leg has washed up on a beach after it was torn off during a horror shark attack — with doctors now scrambling to see if the severed limb can be reattached.

Kai McKenzie, 23, is in a critical but stable condition in a hospital after he was attacked by the great white shark near Port Macquarie in New South Wales on Tuesday, ABC News reported.

Just seconds after being bitten, the surfer miraculously managed to fight off the nearly 10-foot shark and catch a wave back to the beach to get help, first responders said.

“He was very lucky at the time we had a [off duty] police officer that was walking his dog,” NSW Ambulance’s Kirran Mowbray said.

“He used a lead off the dog as a tourniquet to wrap around the young man’s leg and essentially saved the man’s life until the paramedics got there.”

McKenzie — who first responders described as being “calm” and “completely with it” in the immediate aftermath — was rushed to a nearby hospital for treatment.

His severed right leg washed ashore a short time later and was put on ice by locals before it, too, was taken to the hospital.

The surfer and his leg were then airlifted to John Hunter Hospital — a major trauma center more than 120 miles away — where surgeons were assessing if the limb could be saved.

It wasn’t immediately clear if the surgery had been a success.

“He’s just a really brave and courageous young man,” Mowbray said.

McKenzie, who is a sponsored surfer, had only recently returned to the water after suffering a neck injury earlier this year.

A GoFundMe page set up to help cover medical costs has already received more than $116,000 in donations since the attack.