At least three dead and several injured after Greyhound bus collides ...

At least three women are dead after a Greyhound bus carrying 33 people collided with a four-wheel drive towing a caravan on the Bruce Highway in north Queensland. 

The crash occurred on a stretch of the Bruce Highway about 8 kilometres north of the town of Gumlu, between Bowen and Townsville, around 11am on Sunday.

Queensland Police Superintendent Graeme Paine said the car was travelling south and the bus was driving north. All the fatalities and injured passengers were onboard the bus, he said.

Describing the crash as a "very significant incident", Superintendent Paine said one person had been airlifted from the scene.  

He said it was not clear what caused the collision, but it occurred in a 100kph zone.

"It's a crash involving a significant impact," he told reporters.

"We haven't determined any factors that have contributed to the crash at this stage, but certainly a crash of this nature involving this many people is a very significant and very tragic incident for us."

Images from the scene show a badly damaged bus, surrounded by police officers and ambulance workers. (ABC News)

A number of specialists are on scene collecting forensic evidence that will be assessed against any witness statements, Superintendent Paine said.

Anyone with information about the accident, such as dashcam footage, should contact police, he added.

Images from the scene show a badly damaged bus with a crushed front cabin on the highway, surrounded by police officers and ambulance workers. 

Paramedics assessed 27 people at the scene — of those, seven had life-threatening injuries, according to Queensland Ambulance. 

Emergency vehicles gathered at the scene of the crash about 8 kilometres north of Gumlu.(Supplied)

They have been taken to Townsville University Hospital and Ayr Health Service emergency departments.

The Townsville Hospital and Health Service's health incident management team has been meeting to assess the clinical needs of the injured bus patients.

"We have created capacity across our critical care units, including intensive care and emergency, as well as in theatres and inpatient units," said the service's chief medical officer, Dr Jason Yates.

Dr Yates said additional staff had been mobilised to care for the patients.

Members of the community have been asked to stay away from the hospital, unless their matter is serious, as staff treat the injured.

"Staff at both hospitals are currently busy managing patients from the crash," the Townsville Hospital and Health Service said in a social media post.

A CQ Rescue helicopter at the scene of a serious bus crash north of Bowen, Queensland.(Supplied: CQ Rescue )

The Bruce Highway has been closed in both directions, causing serious delays, according to Queensland Ambulance.

Superintendent Paine said it would remain closed for "as long as we need".

Delays have also hit the Queensland Rail service due to the proximity of the crash to rail lines. 

A Queensland Rail spokeswoman said the North Coast line between Bobawaba and Gumlu will remain closed for emergency services to respond to the crash.

The northbound Spirit of Queensland is being held at Proserpine and the southbound Spirit of Queensland is being held at Townsville.

"For those people that may be using the rail, please take this into consideration in relation to your travel," Superintendent Paine said.

Gumlu Tavern owners Toni and Colin Dale said they have opened their business early to give stranded travellers a place to get some water and use the bathroom.