Truck explosion injures eight, closes highway in Queensland - Photos

The truck, carrying ammonium nitrate, exploded after it rolled over near a bridge on a stretch of road between Cunnamulla and Charleville.

The critically injured male truck driver was airlifted to Brisbane, along with a public bystander who tried to assist him.

Four firefighters were also injured, with two still recovering in hospital, along with a police officer and another member of the public.

Charleville Police officer-in-charge Senior Sergeant Adrian Rieck said the Queensland Fire and Emergency Crews were able to remove the driver from the wreck prior to the explosion.

"They were very close, within 30 metres of the wreckage, and at that time there were two explosions within quick succession," he said.

"That has caused catastrophic damage as it was carrying about 56 tonnes of ammonium nitrate."

Senior Sergeant Rieck said the driver, who was critically injured, and a member of the public both sustained serious burns and were airlifted to the Royal Brisbane and Women's Hospital.

Of the injured firefighters, two were transported to Charleville Hospital and two to Toowoomba Hospital.

"The two firefighters treated at the Charleville Hospital have since been released, and the two firefighters treated at the Toowoomba Base Hospital are still recovering in hospital," the QFES said in a statement.

"The fire appliances in attendance sustained extensive damage due to the explosion.

"QFES will continue to monitor the situation as the incident is expected to be protracted for a couple of days."

Senior Sergeant Rieck said a scenes of crime police officer, who "just happened to see the lights and sirens go by" and followed the emergency crews, remained in shock.

"He doesn't appear to be physically injured, but it is like a case of shellshock, I would say," he said.

"We haven't been able to speak to the other people as yet, but it's quite a significant incident for them and we are very, very lucky that no-one was killed.

"I don't know how that hasn't occurred – they were within 30 metres of a 56-tonne blast.

"We don't know how it hasn't killed anyone. We're lucky it hasn't."

Senior Sergeant Rieck said the Mitchell Highway was "closed indefinitely" due to both the damage to the road infrastructure and residual ammonium nitrate.

Geoscience Australia recorded a magnitude 2.0 earthquake in the area at 10.12pm, but a spokesman said it was not related to the explosion.

"It's nothing out of the ordinary and the earthquake occurred about 20 minutes after the explosion, so it's just a coincidence," he said.