SYDNEY - A woman was taken by a shark on Thursday while swimming with her husband in Australia, authorities said, in an attack which horrified fellow swimmers.
Christine Armstrong was with a group of people on a regular swim between Tathra Wharf and Tathra Beach about 350 kilometres (220 miles) south of Sydney when she disappeared.
Reports said the 63-year-old had turned back from the group which included her husband Rob and was on her own when the shark struck.
"Rob was part of the group of five people," police Inspector Jason Edmunds told the Sydney Daily Telegraph. "He saw a shape of a shark he described as 3-4 metres (9-13 feet) long and quite big."
Edmunds said it was not known exactly why Armstrong turned back.
It was not until the others in the group also began their return to the beach and saw a large shark in the water that they became concerned about Armstrong's whereabouts.
"The group joined up together and did their best to keep the shark at bay although it didn't directly attack them," Edmunds added to Channel Nine.
"They made very quick inquiries to see if the other lady was already back at the surf club and unfortunately she wasn't."
Edmunds said a witness had also reported seeing "a large shark mauling something in the water".
"At the end of the day ... there's no sign of the lady and it is quite likely that she has been taken by a large shark," he said.
A body has not been found, nor was the type of shark known, but police said a report would be prepared for the coroner.
The beach was closed as life guards and police searched for the woman while paramedics treated witnesses for shock.
"Emergency services are doing what they can for them but naturally they're shocked and horrified by what's occurred," a police spokesman said.
In a statement, Armstrong's family said she had been swimming at Tathra Beach for 14 years.
"Swimming brought her much joy and many friends," the statement said. "She will be sadly missed by all who loved her, especially by Rob, her husband of 44 years."
While sharks are common in Australian waters, deadly attacks are rare, and Bega Valley Shire Council general manager Leanne Barnes said the small town was stunned.
"It's a very popular, sensationally beautiful part of the far south coast," Barnes told ABC television.
The attack follows a presumed death in February when a man went missing while spear-fishing off the South Australia coast in the same week that a great white shark was reported in the area.
And on Wednesday the body of a diver who vanished in Western Australia at the weekend was recovered, with police saying there was evidence he had been bitten by a shark.
According to the Australian Shark Attack File based at Sydney's Taronga Zoo, the last unprovoked fatality in the same state as Thursday's attack - New South Wales - was in 2013 at Coffs Harbour north of Sydney.
There have been 168 fatal attacks over the past 100 years, it said.