Truck explosion site 'still unsafe'

A two-kilometre exclusion zone remains in place over a day after a truck carrying volatile chemicals in outback Queensland exploded.

Four firefighters and a policeman were among eight people injured when a truck carrying 50 tonnes of ammonium nitrate exploded on the Mitchell Highway, about 30km south of Charleville in southwest Queensland, on Friday night.

The explosion occurred as emergency crews responded to reports of a truck rollover.

The force of the blast destroyed a bridge, cutting off the main route between Charleville and nearby Wyandra.

It also severely damaged two fire trucks at the scene.

Tom Dawson, the Assistant Fire Commissioner for the south-west region, told the ABC: “We still actually believe we've got a little pocket of ammonium nitrate burning, so that in itself, with the fumes that'll come from that burning process, still indicates we've got an unstable situation.

"It's going to be a very scientific call to say it is now stable, then we'll go about it very guardedly to go closer to determine the degree of safety.

"We now believe a lot of the product is actually buried under earth."

A bridge destroyed when the truck exploded. Photo: Queensland Police

Charleville residents reported feeling the blast shake their homes.

"At my oldies (sic) place near the scout hall ... a boom, rumbling thunder sound from the south east, passed through the house rattling the ceiling and windows," Mark Scott wrote on Facebook.

"We looked at each other, mum said `that's a bloody big possum jumping over the roof!'"

Paula-Ann Russell said she felt "the whole house moving".

A Geoscience Australia spokesman said several concerned residents had reported an earthquake.

Ironically, the spokesman said there was in fact a small magnitude-2 earthquake recorded south of the accident site shortly after the explosion.

Magnitude-2 earthquakes are not usually felt.

The male truck driver sustained serious, but not life-threatening, injuries and was airlifted to Brisbane.

A Queensland Fire and Emergency Services (QFES) spokesman said two of the four injured firefighters were still recovering in hospital after the incident.

The police officer, the two other firefighters and two men who witnessed the crash all received minor injuries and were taken to Charleville Hospital for treatment.

Investigations into the incident are continuing.

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

Truck drivers have been advised to avoid the accident site, while a detour has been set up for smaller vehicles.

An overhead of the crash site and the destroyed bridge. Photo: Seven Network