'Very, very confronting': 3 women have been killed in a bus crash in Queensland.

Three women are dead after a horror bus crash in North Queensland which left first responders dealing with a "very, very confronting" scene.

The Townsville Hospital and Health Service (THHS) reported that seven patients—five men and two women—were taken to Townsville University Hospital for treatment.

By early Sunday evening, two women and one man had been discharged from the hospital.

On Monday morning, a THHS spokesperson confirmed that four men were still hospitalised. Two of them, aged 23 and 24, were in critical condition, while the other two, aged 27 and 51, were reported to be in stable condition.

Emergency services attended the Bruce Highway near Gumlu, in the Whitsundays region, shortly after 11 am on Sunday.

Image: Getty.

Police said a four-wheel drive pulling a caravan collided with a Greyhound bus carrying 33 people in the opposite direction in a 100km/h zone.

Along with the three fatalities, a number of people were treated at the scene, with one man airlifted to a nearby hospital due to the severity of his injuries.

Police did not confirm the identities or ages of the people killed, nor did they speculate as to the cause of the incident.

"The crash is under investigation, 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, very tragic incident for us," Superintendent Graeme Paine told reporters.

He acknowledged the "very significant impact and very significant consequences" of the crash, encouraging anyone not coping well with the trauma to access support.

"A crash like this is very, very confronting, and the first responders and the community members on scene at the time have done a very significant job in trying to help those who are injured and safeguard the scene and try and assist those who need medical attention," he said.

"This is an incident which impacts people, and it will not just impact those that are immediately involved in the incident, but also those that have helped, and also the local community and extends through to the family members involved."

The bus was heading to Townsville, around one and a half hours from where the crash took place.

Greyhound Australia's CEO, Dan Smith, said they were "heartbroken" about the incident.

"This is a tragic incident and our deepest sympathies go out to those involved and their families and friends," Mr Smith said.

"We are working closely with authorities to assist them with their investigation in understanding the course of events that have led to this accident. We are also providing support to members of our team impacted by this tragedy.

"We will provide further updates as more information becomes available and ask that you respect the privacy of those involved at this extremely difficult time."

The bus involved was the service GX402, travelling from Brisbane to Townsville.

The Bruce Highway is experiencing significant delays, with police urging people to avoid the area.

Supt Paine wouldn't speculate when asked if fatigue was a factor in the crash.

"It's in the early stages of the investigation and I'm not going to speculate as to a cause," he said.

"There'll be a number of investigative avenues pursued to try and determine actually what happened."

Feature image: Queensland Government.