More than 20 passengers were injured, 12 seriously, on a tourist boat which ran into trouble off the Kimberley coast in Western Australia.
On Friday, the Royal Flying Doctor Service led the emergency response to the incident at Horizontal Falls, around 250km north-east of Broome.
Four planes with six doctors and six flight nurses were deployed to the scene, assessing and treating patients on the boat.
The first group of slightly injured patients were flown by seaplane to Broome Hospital for further assessment.
About 12 seriously injured patients were to be transferred to Perth or Broome for treatment.
Authorities said local helicopter services were providing assistance to winch some patients to safety.
Perth Police said they understand the incident involved the capsizing of a tourist vessel, but this has yet to be confirmed.
Tour operator Horizontal Falls Seaplane Adventures said in a statement it was working with authorities to help injured passengers and manage the incident.
“Falls Express, guided by an experienced skipper on an early morning excursion, was involved in the incident as it traversed the falls,” the statement reported by the ABC said.
“The ship immediately returned to the pontoon.”
The company said 26 passengers and two crew members were on board at the time.
Broome Police said the incident was ongoing, but none of the injuries were believed to be life threatening.
The area hosts regular jet boat trips through the fast-moving Kimberley tides.
The falls are a natural phenomenon where 10m of water gushes through two narrow chasms in Talbot Bay.