UPDATE 3.20PM: A BLAZE which fully engulfed a bus on the side of Ridgelands Rd, Alton Downs this afternoon has been deemed not suspicious.
A Queensland Police spokesperson said when police arrived about 1.25pm there were no passengers aboard.
The spokeswoman said police inspected the scene and assisted with traffic control as the incident closed both lanes of the Alton Downs road.
"The fire was not suspicious, they saw smoke under the hood and an oil leak before it happened," she confirmed.
UPDATE 2PM: TRAFFIC backed up Ridgelands Rd as fire crews battled a bus blaze which spread to nearby bushland.
The fire broke out about 1pm, with one witness saying they doubled back in their vehicle after seeing smoke, and soon heard an explosion from the bus.
Four Queensland Fire and Emergency Service crews had extinguished the bus fire as of 1.30pm, and were dampening down hot spots.
Queensland Police Service arrived on scene at 1.25pm, and began to move traffic slowly through from both directions.
A QFES spokesman said investigations are left in the hands of the Criminal Investigation Branch.
The Queensland Ambulance Service were on scene, but it appears no one was treated for injury.
UPDATE 1.35PM: POLICE are requesting the Rockhampton Criminal Investigation Branch to attend the scene of a bus fire in the 100km/hr zone on Ridgelands Rd.
While fire crews have extinguished the blaze on the bus, they are still working to contain a bush fire on the side of the road.
Police have opened one lane of the road and are directing heavy traffic through one lane.
UPDATE 1.15PM: ALL passengers are reportedly out of the bus and fire fighters are attempting to extinguish the blaze.
Fire fighters are also fighting a bushfire sparked by the bus fire.
Queensland Police are responding to provide traffic control as the bus is on the road and both lanes of the road is blocked.
BREAKING 1PM: EMERGENCY services are responding to reports of a bus fire at Ridgelands.
Initial reports suggest the bus is alight on the corner of Ridgelands Rd and Laurel Bank Rd and fire has spread to bushland.
It is unclear at this stage whether anyone has been injured.
Queensland Fire and Emergency Services, Queensland Ambulance and Queensland Police crews are en route.
More updates to come.