Authorities in the city of Cairns said that they had not confirmed the identity of the pilot, his reason for making the flight or how the tourist helicopter was able to take off from Cairns Airport.

A couple staying at the hotel was hospitalised suffering from smoke inhalation and have now been discharged, Queensland Police Service Acting Chief Superintendent Shane Holmes told reporters. No one else on the ground was hurt.

Holmes said it was not known if the man flying the helicopter held a pilot's license or if he worked for the company that owned the craft, Nautilus Aviation.

“There is no further threat to the community, and we believe this is an isolated incident,” Holmes said.

Nautilus Aviation said in an unattributed written statement that the flight was “unauthorised” but would not supply any further details.

Cairns Airport CEO Richard Barker said initial findings of a review Monday showed “no compromise of the airport security program or processes."

About 400 people were evacuated from the hotel after the crash, which happened in the early hours of the morning in a busy tourist district of Cairns — a tropical city of 150,000 people in far north Queesland — where it is peak season for holidaymakers. Witnesses told local news outlets the crash sounded like a bomb exploding.

Smoke and flames billowed from the roof of the Doubletree Hilton and one of the helicopter's rotor blades landed in the hotel pool, the Australian broadcaster ABC reported.

The hotel remains cordoned off while its structural integrity is being examined.