Woman serious but stable after shark attack in Adelaide

A woman is in a serious but stable condition after being attacked by a shark in Adelaide's south this afternoon.

Emergency services were called to Port Noarlunga jetty just after 1pm after reports a 32-year-old woman had been bitten by a shark.

She was rushed to Flinders Medical Centre with injuries to her scalp and face, which were earlier described as "extremely serious" and "life-threatening" by SA Ambulance.

9News understands that she will most likely have to undergo surgey.

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The woman was free-diving with a friend when she was attacked, according to witnesses.

"Police with the assistance of other emergency services evacuated the water while a search to locate the shark was undertaken," police said in a statement.

"Members of the public have since returned to the water after the search failed to locate the shark."

The beach was full of school kids who were out on a pupil free day, while others were there for aquatic lessons.

Some of the children claimed to have witnessed the shark grab the woman by the head.

"Some of the kids did see it, we've been talking to a few of them and they saw her face all bloodied," swimmer Mason Corbett told 9News.

Surf Life Saving South Australia monitored the area for hours after the attack, keeping an eye out for the shark.

It is the fourth shark attack off the South Australian coast this year.

A 55-year-old surfer, Todd, is believed to have been killed by a shark off Granites Beach near Streaky Bay.

His body was never recovered but a part of his board and wetsuit were found.

A 64-year-old woman, Pam Cook, survived being bitten while swimming at Beachport.

Simon Bacanello's body was never found after the teacher was attacked while surfing off the state's west coast in May.

More to come.