Canberra, Sept. 7 -- A childhood friend described the "heroic" final act of a surfer who steered his friends to safety before being mauled by a shark at Sydney's Northern Beaches, as authorities race to find the shark, ABC News reported.

A frantic effort has been underway to find and identify the species and size of the shark after it claimed the life of Mercury Psillakis in a morning surf at Long Reef Beach.

Psillakis, a 57-year-old who is survived by a daughter and wife, suffered catastrophic injuries in the attack on Saturday.

He routinely walked the couple of hundred metres from his home to the beach to go surfing, former professional surfer and friend Toby Martin said.

"A really deep loss for us on the eve of Father's Day for an ...