Hundreds of guests staying at a hotel in Cairns, Australia, have bee forced to flee the building after a helicopter crashed into the roof, causing a fireball and billowing black smoke.

Around 400 people were evacuated from the Double Tree Hotel by Hilton on the city's waterfront after the dramatic incident, with Queensland Poice imoosing a wide exclusion zone around the building.

While emergency services respond to the apparent helicopter crash, police have arricaded off swathes of Esplanade, Minnie Street, Aplin Street, and Grafton Street for public safety. Additionally, officials issued a Public Safety Preservation Act (PSPA) notice.

The crash happened around 1.50am on Sunday morning at the hotel situated on the Esplanade, with the ambulance service initially reporting no injuries among people on the ground. Two hotel residents were taken to the hospital, a man in his 80s and a woman in her 70s, but both were said to be in a stable condition.

Queensland officials, after some initial confusion, have stated that there was only one person on board the helicopter

Videos of the aftermath were quick to circulate on social media, showing the fire engulfing the roof after the helicopter's impact, which sent propellers flying into nearby buildings, with one found in a hotel pool, still on fire.

One woman on Facebook shared a video of the fire lighting the morning sky, saying: Boy, that was going fast, that helicopter, too.

"Unbelievable. Red helicopter. Went past twice, it’s just going out of control that thing was."

The damage caused by the helicopter impact is not yet known, with emergency services cautious to enter the building after the huge fireball, which some hotel guests described as "sounding like a bomb."

Queensland Ambulance Caitlin Denning spoke to the local media in the aftermath of the calamitous crash, saying: “At the time, it was too unsafe for us to enter the hotel to view. The helicopter impacted the roof of the hotel, however two propellers have dislodged.

“One landed on the Cairns Esplanade and there was a second propeller located in the hotel pool on the bottom floor and it was on fire.”

Cairns, a city known as the gateway to the Great Barrier Reef, lies in the tropical northeast of Australia's North Queensland. It is a well-known tourist are and has a population of approximately 153,181 people.