UPDATE:
Mandurah surfer Ben Gerring was in a critical condition at Royal Perth Hospital on Wednesday morning as authorities began hunting the shark that attacked him in waters off Falcon Beach.
A Department of Fisheries vessel was seen hunting the shark early Wednesday morning.
A spokesperson said shark capture gear had been set at Surf Break Lookout, near Falcon, after the attack.
He said there was still a serious threat to public safety and the beach remained closed.
It is believed that given the nature of the injuries and the location of the incident, it is likely that a white shark, of 3-metres or more in size, is responsible for the attack.
The City of Mandurah has closed the beach.
Witnesses to Tuesday afternoon’s shark attack in Falcon were in shock, with the victim, a male surfer, taken to hospital.
The attack happened just before 4pm at Gearies beach, just south of Mandurah.
Mr Gerring, who is a member of Mandurah Board Riders, was surfing with others when an unknown species of shark struck.
He lost a leg and was rushed to Peel Health Campus after being given CPR on the beach.
Mandurah Board Riders president Brian Williams said he knew the victim well and had been about to paddle out when the attack happened.
“On any given day there’s probably around about 50-60 people in the water,” he said.
“I’m not sure but I think this would be the first time it’s ever actually happened here.”
The rescue helicopter was initially called, but was later stood down.
It has since been called back to transport the man to Royal Perth Hospital.
The beach surrounding the attack has been closed with rangers and Fisheries advised.
There has never been a fatal shark attack off Falcon, or off any beach in Mandurah.
In March 2014, local man Mick McGregor disappeared while scuba diving about 5 kilometres off Dawesville.
His body was later found with bite marks, but the cause of his death was never confirmed as a shark attack.