Greyhound bus passenger shares what happened in minutes after deadly Bruce Highway crash at Gumlu

A survivor of a deadly bus crash has revealed what happened in the terrifying moments after the collision that killed three people in Queensland.

A woman in her 20s, another in her 30s and a 56-year-old grandmother died after a Greyhound bus collided with a caravan being towed by an elderly couple on the Bruce Hwy at Gumlu, south of Townsville, on Sunday.

WATCH THE VIDEO ABOVE: Passenger details deadly Queensland bus crash.

Two men aged 23 and 24 are fighting for life and two others, aged 27 and 51, remain in hospital in a stable condition.

Mikayla was on the bus travelling home from a wedding and said she “immediately got into a brace position”.

The bus, carrying 33 people, was heading north towards Townsville in a 100km/h zone when it collided with the caravan travelling in the opposite direction.

The impact forced the bus off the road and it came to a stop on the adjacent train tracks.

“When we came to a standstill the bus driver and a couple of civilians came in, they worked together to open the door and just get everybody out,” Mikayla said.

Bystanders who gave first aid while waiting for emergency crews to arrive have been praised for saving lives.

Police described the scene as “very, very confronting”.

The cause of the accident is still being investigated and fatigue will form part of the police probe.

Long-distance coach drivers must abide by national heavy vehicle regulations, the same as truck drivers.

Greyhound would not provide a response to 7NEWS when questioned about its fatigue management policy on Monday.

Forensic crash police are understood to be studying dashcam video and interviewing passengers.

“I think it’s premature to be speculating on the cause our investigators will do what they do best and that is identify what exactly has happened here,” Queensland Premier Stephen Miles said.