A British couple and two Australians died in Australian Helicopter crash on Monday near the Sea World resort in Queensland.
Further report proves that three others including two children were seriously injured in the crash.
Officials say it happened less than 20 seconds after one helicopter took off from a sandbar and collided with another aircraft that was landing.
“What we do need to know now is what was occurring inside those two cockpits at the time,” air safety commissioner Angus Mitchell said.
All those killed and critically injured were in the ascending helicopter, which crashed within seconds after its main rotor blade struck the cockpit of the other aircraft.
The landing was a “remarkable achievement” given the helicopter was damaged “where the pilot was sitting”, Mr Mitchell said.
“We are very fortunate that we’re not standing here with far more deaths,” he told reporters on Tuesday.
The UK victims were Diane and Ron Hughes from Merseyside – aged 57 and 65 – who were married and had next of kin in Australia.
Australian media reported that 36-year-old Vanessa Tadros also died in the crash, and her 10-year-old son was among the survivors hospitalised in a critical condition.
The fourth victim was 40-year-old Ashley Jenkinson, an experienced Sea World Helicopters pilot who lived in the area.
A boy, 10, and a woman, 33, remained in a critical condition in hospital on Tuesday, police said. A nine-year-old boy with serious injuries was described as stable.
Both helicopters were operating tourist flights for Sea World – one of several popular theme parks on the Gold Coast. Its owner, Village Roadshow Theme Parks, has offered condolences and said Sea World Helicopters is an independent operator.