Kill order issued for 4m shark that attacked NSW bodyboarder

Authorities will today start the hunt for a shark that attacked bodyboarder Matt Lee on a northern NSW beach, leaving his legs severely injured.

A helicopter will be launched this morning with permission to kill the four-metre shark under strict conditions.

The hunters have to be sure the predator they target is the same one that attacked the 32-year-old body boarder at Lighthouse beach in Ballina yesterday morning.

It has to also be established the shark is an immediate threat to other ocean-goers in the area.

A junior surfing competition with about 200 competitors is taking place just north of Lighthouse beach, sparking fears the shark could move to this area.

Mr Lee remains in a critical condition at Gold Coast University Hospital, with serious injuries to his legs.

He has received a significant blood transfusion, while surgeons are now working out a plan to treat the rest of his injuries and combat the threat of infection.

9NEWS understands that a tooth was found in the man's wounds.

A male witness who dialled Triple Zero said both of the victim’s legs had been injured.

“It wasn’t very nice, but I got down right next to him, and relayed all the information, and the paramedics came.

“It was both legs, but one was really bad, as far as I could see,” he told 9NEWS.

Another witness said bystanders rushed to the victim's aid.

"All I could see was a lot of blood on a blanket around his legs," a man who declined to be named told 9NEWS.

“His mate who brought him in, he was in shock."

Yesterday's attack occurred near the site of a fatal mauling earlier this year.

Japanese national Tadashi Nakahara, 41, died at nearby Shelly Beach after he was bitten on February 9.

A teenager died in 2008 at the south end of Lighthouse beach near the mouth of the Richmond River.

The shark had bitten 16-year-old body boarder Peter Edmonds twice.