A firefighter has been seriously injured in a frightening crash after a fire truck ploughed into a tree south of Brisbane.

Station Officer Mitchell Rogers was behind the wheel on Beaudesert Beenleigh Rd at Mundoolun about 9.50am on Monday when the vehicle veered off the road and slammed into a tree.

The 15-year veteran from the Queensland Fire Department was the only person onboard and became trapped in the wreckage.

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His own colleagues rushed to the scene and had to cut him free.

Paramedics and a High Acuity Response Unit treated the man before taking him to Princess Alexandra Hospital.

Rogers was initially believed to be in a life-threatening condition with lower limb injuries, but is now in a stable condition.

Police said Beaudesert Beenleigh Rd was closed for several hours.

Motorists were advised to avoid the area or seek an alternative route.

Investigators believe wet weather may have played a role in the crash.