Tributes to victims at Gold Coast helicopter crash site as long investigation begins

Floral tributes are growing at the site of the deadly Gold Coast chopper crash that killed four, as the long investigation into what caused the disaster begins.

Crash site investigators have removed the final pieces of wreckage from the Broadwater on the Gold Coast as they try to piece together how two Sea World helicopters collided mid-flight.

Police divers left the scene shortly before 6pm yesterday (7pm AEDT) after spending the afternoon combing through and removing the final pieces of the wreckage.

READ MORE: Sydney mum killed in Sea World helicopter crash, son fighting for life

Investigators had arrived at first light to conduct the careful task of moving away the two helicopters after the tragedy that claimed the lives of four people, including three tourists.

Another three people are fighting for their lives, as more details come to light about the horrific incident.

Floral tributes are beginning to grow at the site of the tourist hotspot.

Hundreds of witnesses who watched the events unfold yesterday are now providing statements to police, describing how onlookers rushed to the sandbank to help.

The wreckage and electronic monitoring equipment are being analysed to discover how the two aircraft collided on a crystal clear day.

READ MORE: 'I couldn't imagine anyone surviving that': Man tells of chopper terror

The moment things went horribly wrong took place as one helicopter was coming in to land while the other was taking off.

The second chopper spent less than 20 seconds in the air before the crash.

Investigators believe the ascending helicopter took off from the pad into the path of the descending chopper, its rotor-blades smashing into the left side of the other aircraft, sheering off its windscreen, before coming apart, leaving the fuselage to fall to the sandbar.

Despite the collision, an injured pilot managed to bring one helicopter to land on the sandbar, albeit without a windscreen.

The other aircraft crashed.

Its pilot, Ash Jenkinson, 40, British nationals Ron and Diane Hughes, 65 and 57, and Sydney mum Vanessa Tadros, 36, died at the scene.

Queensland Police described it as "a very very confronting scene".

"My heart goes out to those people who came here to have a beautiful time on the gold coast and have tragically passed away here," Police Commissioner Katarina Carroll said.

The three others in the downed helicopter were critically injured: Tadros' young son and Winnie De Silva and her son Leon.

The six in the second helicopter are alive, some of them suffering shrapnel injuries.

"Whilst it has been very tragic that four people have lost their lives and many families are mourning this morning, we could have had a far worse situation here," Australian Transport Safety Bureau Chief Commissioner Angus Mitchell said.

"And the fact that that one helicopter managed to land has been quite remarkable."

The company behind the incident, Sea World Helicopters, say their staff are devastated but won't be making any further comments at this point.

The preliminary investigation by the Transport Safety Bureau will take weeks if not months, with the main question around protocols of aircraft coming and going from the busy theme park.