A South African man was killed by a shark while swimming at Second Beach in the rural Eastern Cape region.
The beach is one of the world's deadliest spots for shark attacks, officials said on Monday.
The beach has been closed until further notice.
Lungisani Msungubana, 25, had been swimming in waist-deep water with friends when the shark attacked him.
John Costello, local station commander for the National Sea Rescue Institute, said Msungubana sustained "multiple traumatic lacerations to his torso, arms and legs" where the shark bit him repeatedly.
"At the clinic medical staff declared the man dead after all efforts to save him had been exhausted," said Costello.
The attack is believed to have been carried out by a Bull Shark.
According to the national rescue authorities, the beach located in the town of Port St Johns is one of the world's deadliest for shark attacks. The beach has experienced six fatalities in six years, with three of them occurring in 2009 alone.
In January 2011, a teenage surfer was killed in a shark attack witnessed by onlookers.
"The Natal Sharks Board are currently carrying out studies in an effort to try to determine why there has been such a... spate of shark incidents in Port St Johns," Costello said in a statement.
Pictures taken on Sunday show lifeguards wading nervously into the sea to pull the badly-injured Mr Msungubana to safety. Costello said they placed him on a surfboard to bring him to shore where he was treated by a doctor who had been on the beach before paramedics arrived.
Experts from the Natal Sharks Board have been brought in to investigate the incident, and the repeated occurrences of shark attacks at the beach, and town authorities have closed the beach to swimmers.