A surfer is fighting for his life in hospital after a shark ripped off his leg in an attack off Western Australia.

Local officials later caught a 15ft great white shark near the site where 29-year-old Ben Gerring was mauled at Falcon, south of Perth, and warned swimmers in the area to stay out of the water.

Mr Gerring was attacked at around 4pm local time on Tuesday. Witnesses described how the surfer had paddled out quite far to catch a big wave when suddenly "all hell broke loose".

Ambulance and police officers help a critically injured surfer after a shark ripped off his leg in an attack in Western Australia (AFP/Getty Images)

According to local media reports, Mr Gerring’s board was broken in half in the course of the attack, with other surfers only able to find the tail part.

A heavy machinery operator, Australian national Mr Gerring was airlifted to hospital in Perth where he was described on Wednesday as being in critical condition.

Nathan Hondros, a Mandurah Mail reporter who arrived on the scene shortly after the attack, told the Associated Press: "A couple of the guys with longboards brought him in to the shore. So, it was obvious he wasn't in a good way and they were huddled around and in tears. It was really desperate scenes.

Australia: Shark attacks 29 y/o surfer south of Perth

"He was unconscious. He'd lost his leg from above the knee so it was pretty horrific injuries. It was terrible to watch, there was a lot of distressed people on the beach.

"There were kids who were in the water surfing with him so it was a really, really difficult thing to watch.”

Brian Williams, president of the Mandurah Boardriders Club and friend of the victim, told ABC: "He was right out the back looking to get a big wave, one of the set waves that had been coming through during the day.

"He'd sort of paddled out the back, sort of past the pack slightly. And next thing all hell broke loose and they were trying to bring him in."

Witnesses said the suspected great white surged up out of the water during the attack (Getty)

According to Perth Now, officers from the Department of Fisheries deployed a set of baited drums at the location where the attack took place at first light on Wednesday.

Shortly after 3pm local time – around 24 hours after the attack – they reported that a great white shark measuring between 3 and 4.5m had been hooked.

Surfer Paul Collier, who was in the water at the time of the attack, told the local news outlet he saw a large shape – presumably the shark – surging up from the water.

"When it was a full, up-in-the-air type thing, I knew it was a pretty heavy shark attack," he said.

"His leg was really badly ripped off. . . I'm not trying to dramatise it but it was fricken really bad."

Western Australia has experienced particular problems with shark attacks in recent years, and in 2013 the state government sparked controversy by announcing a plan to indiscriminately cull sharks above a certain size.

The cull was ended a year later after scientists questioned the effectiveness of such a policy.