The man has now been discharged. It is understood he received "dozens" of stitches.
"There was a group of guys coming in and they were starting to walk back up the beach waving their boards around," witness Stuart Holland told Nine News.
"One of them was definitely limping, had blood running down from the bottom of his wetsuit, quite a lot of blood.
"They were waving their boards trying to indicate to other surfers. At that point I started to panic about my kids.
"[They were] paddling out to where the main pack was, which was thinning down by that point because obviously they'd heard, but my kids hadn't."
Mr Holland's daughter, Belinda said: "His board went flying into the air.
"He got a massive chunk out of his leg and his side and it was a lot of blood. It was pretty freaky."
An image of a man with cuts to his leg was posted to Twitter following reports of the attack.
User Geoffrey John Knapp posted the image, which has now been deleted, with the caption: "One very lucky surfer today at Broken Head NSW Australia."
Another dude just got attacked by a shark at Broken, 100m from me 😳 luckily he is fine apart from a few teeth holes in his thigh. Fuck
Posted by Aaron Hoffman on Sunday, 23 October 2016
Lifeguards and police closed all beaches in the Byron Bay area. It is the third shark attack in the northern NSW region in a month.
Sharks have been previously spotted swimming among surfers in the popular surfing area.
The last shark attack at Broken Head was in February 2015 where a surfer was hospitalised with lacerations to his back after being lashed by a two to three metre shark.
The popular surfing spot is about 25km north of Ballina, where a series of incidents has prompted the NSW Government to rethink its shark strategy.
Since February last year there have been four attacks along a 1km stretch of Ballina coastline, including one fatal incident.
