Beachgoer Mark Hickey swam 15 to 20m into the water at Clarkes Beach to retrieve the severely wounded victim, Paul Wilcox, a 50-year-old British man, Police Inspector Bobbie Cullen said.
He received medical treatment on the beach but did not survive, Cullen said.
“A gentleman who was on the beach went out and located the gentleman and pulled him in,” Cullen told reporters. “Absolutely it is (an extraordinary act of bravery) and we can only thank him for his efforts.”
Hickey, a 52-year-old lawyer on holiday at Byron Bay, told Ten Network television news that he saw the shark and its bloodied victim and swam out to try to rescue the man as the shark attacked again.
“I went out there and, I don’t know, I just thought I’ve got to get this guy in and that’s what I tried to do,” Hickey said.
He said Wilcox had apparently bled to death in the water. It was reported the shark had bitten through the victim’s wetsuit on his right thigh, tearing off much of his leg. The wounds were being examined to identify the species of the shark.
The victim’s wife was on the beach at the time of the attack.
Cullen said the crew of a rescue helicopter spotted what appeared to be a great white shark later but lost sight of it. She said all Byron Bay beaches would be closed for 24 hours due to the potential danger.
Byron Bay is a renowned surfing location near Cape Byron, about 800km north of Sydney.
The last fatal shark attack in Australia was April 3, when a 63-year-old woman was taken by a 13ft shark near Tathra, 340km south of Sydney.