SYDNEY, Sept. 21 (Xinhua) -- A second shark attack at the same location in under 24 hours has prompted Australian authorities to advise tourists against swimming there until they can establish the threat.

A 46-year-old Australian woman is lucky to be alive after being mauled while swimming in Cid Harbour in the north-easterly Whitsunday Islands on Wednesday evening.

Less than 24 hours later a 12-year-old girl on holiday from New Zealand received life threatening wounds to her leg while snorkelling in the same harbour.

Both victims were transferred to hospital by medical rescue helicopter and have undergone multiple blood transfusions and emergency surgery to stabilise them.

Authorities have said that the occurrence is highly unusual and have deployed baited drum lines in an attempt to catch the offending shark, or sharks.

"It is possible that there's more than one shark involved in these unfortunate events," Queensland Fisheries' shark control program manager Jeff Krause told the national broadcaster.

"We don't normally go out and search for any sharks that may have been involved in a shark attack but due to the nature of these multiple attacks, Queensland Fisheries is going to deploy three drum lines in a bid to try and catch some of the sharks in that area."

Krause said various types of whaler species as well as bull and tiger sharks can be found in waters around the harbour and he advised against swimming in or near Cid Harbour for the time being.