An emergency was triggered after a helicopter crashed into the roof of a hotel in Far North Queensland.

Police declared a Public Safety Preservation Act (PSPA) in Cairns after the chopper crashed into the building shortly before 2am local time on Monday.

The PSPA has an exclusion zone encompassing the city’s Esplanade and Minnie, Aplin and Grafton Sts.

Queensland Ambulance Cairns senior operations supervisor Caitlin Denning said 300-400 people were being evacuated from the Double Tree Hotel as crews arrived.

“At the time, it was too unsafe for us to enter the hotel to view the [impact site],” she said.

“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.”

Members of the public are being warned to avoid the area.

There are no reports of injuries to people on the ground, police say.

No word has been issued about the fate of those on board the helicopter.

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Denning said the noise generated by the impact was frightening.

“There were reports of it sounding like a bomb, and seeing the fire and smoke, a lot of the occupants of the hotel were unsure of the situation.

“There is a lot of unease here.”

Officers are on the scene investigating the incident.