The incident forced competition to be suspended at the nearby Margaret River Pro, but the action resumed a short time ago.
An ambulance headed to the scene to treat the latest victim, Jason Longgrass, who was attacked at Lefthanders surf break, near to Cobblestones surf break, where a man was bitten on the leg about 8.20am.
"He is conscious and breathing and being treated for leg injuries", St John Ambulance said in a tweet.
Surf photographer Peter Jovic told the ABC news he had witnessed the attack. "There was a lot more thrashing around".
Friends used the rope from the victim's board as a tourniquet and gave him first aid until emergency crews arrived from Margaret River within six minutes, AAP reported. [I] saw the guy who had been attacked get separated from the [surf] board and then start to paddle for an inside wave, which he managed to body surf all the way in.
"Surfer and staff safety are top priorities for the World Surf League", a spokeswoman said.More news: Woman confined, raped by 'friend' for 10 days
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Justin Longrass was bitten at Lefthanders beach about 2.30pm, by a shark estimated at four-metres long.
With all eyes on the nearby contest at Margaret River, WSL officials chose to put the event on hold-and considering Mick Fanning's close call at the J-Bay Open in 2015, it seems like a good call.
"Further enhanced safety measures, including ski and drone presence, will be added to the event's mitigation protocols".
According to ABC, Hawaiian pro surfer John John Florence had a close shave with sharks while surfing in the area just before the competition.
Opposition Leader Mike Nahan said the attacks emphasised the need to do more, including using SMART drumlines rather than the WA Labor government's subsidised deterrent devices.
Hareb and Australia's two-time world champion Tyler Wright were the first surfers to hit the water for their round two heat after the shark scare.