A British couple were among four killed in a mid-air collision that left two mangled helicopters on a sandbank near an Australian tourist hotspot, investigators said Tuesday.
One helicopter was taking off for a "tourist joy flight" along Queensland's scenic Gold Coast when its rotor blades smashed into the cockpit of another helicopter coming in to land, air safety commissioner Angus Mitchell said.
"In the process of that collision the main rotor blades and gearbox of the helicopter taking off have separated from the aircraft, causing it to tragically crash down on to a sandbar," he told reporters.
Both helicopters were operating out of Sea World, Mitchell said, a popular theme park and aquarium.
There were seven people on board the helicopter that was taking off -- the pilot and six other passengers.
Three adult passengers were killed, police said Tuesday, alongside pilot Ashley Jenkinson.
The other three passengers were in critical condition.
Queensland Police Inspector Mike Campbell said two British nationals, believed to be a husband and wife, were among the dead.
Jenkinson was a skilled pilot who had flown rescue missions during Australia's recent flooding disaster, friend Andrew Taylor told national broadcaster ABC.
All six people on the second helicopter survived -- which "remarkably" landed upright nearby despite having its cockpit obliterated, investigators said.
"Whilst it has been very tragic that four people have lost their lives and many people are in mourning, we could've had a far worse situation here," said Mitchell, from the Australian Transport Safety Bureau.
"What we do need to know now is what was occurring inside those two cockpits at the time."
Police said local boat owners rushed to the "confronting" scene to help crash survivors.
"They did their very best with CPR until the emergency services got there," Campbell said.
A preliminary report was expected in between six to eight weeks.