A 12-year-old girl who was bitten on the leg by a shark at Cid Harbour in the Whitsundays has arrived at Mackay Base Hospital in a critical condition.

It was the second shark attack in the area in 24 hours.

Tracey Eastwick, an operations manager for Queensland Ambulance Service, said the situation was horrific.

"For us, as a community of paramedics, it is quite confronting to have two similar incidents in the space of less than 24 hours," she said.

"The injuries today are again a shark attack maul bite to the patient's thigh area with significant blood loss and serious injuries.

"It was a wonderful job done by the first-aiders.

"They were very large wounds.

"She was bitten just below the groin."

The view from onboard the RACQ CQ Rescue helicopter as they head to Whitsunday Island. ( Supplied: RACQ CQ Rescue )

Ms Eastwick said a paramedic was sent from Hamilton Island on a police boat to help the girl.

The RACQ CQ Rescue helicopter was also called and landed on a beach very close to the harbour.

A doctor and paramedic were transferred to the boat to stabilise her, and her father accompanied her on the rescue helicopter.

"It was extremely traumatic for the family."

Ms Eastwick said the girl remained conscious throughout the flight and received multiple blood transfusion among other fluids.

She will go into theatre this afternoon to be further stabilised.

Cid Harbour, on Queensland's Whitsunday Island, is a popular spot for charter boats and private yachts. ( Facebook: RACQ CQ Rescue )

Shark control measures to be installed Friday

Mark Yates, who is boating in Cid Harbour and was 60 metres away from the first rescue, heard the latest call for help over the marine radio.

"Fisheries [Queensland] have come around just after the helicopter took off from the beach and they've warned everybody about swimming and made everyone aware of what's been happening," he said.

The Fisheries Department will deploy three temporary drum lines in Cid Harbour at first light on Friday, and have advised the Great Barrier Reef Marine Park Authority of the move, which is permitted under the marine park zoning plan.

On Wednesday, Tasmanian woman Justine Barwick was flown to Mackay Base Hospital after she was mauled on the leg by a shark.

Ms Barwick — who works for Family Based Care in north-west Burnie in northern Tasmania — was pulled out of the water and onto a nearby yacht, which happened to have a doctor on board.

She remains in a critical condition.