Three people are in a serious condition in hospital after a head-on crash on Bribie Island bridge.

The fiery two-car crash happened just before 12.30pm and closed the bridge to all traffic. It was expected to remain closed for several hours.

Initial reports indicate a large amount of fuel was spilt from one of the cars, causing a fire that could be seen from several kilometres away.

A QFES spokesman confirmed that at least one car caught on fire as a result of the crash, with "a large amount of fuel" being leaked from the vehicle.

The driver of one of the vehicles is alleged to have fled the scene on foot before police officers tracked the man down.

It's understood he is well known to police.

Three patients were taken to hospital in serious conditions with chest and abdominal injuries. Two went by lights and sirens to the Royal Brisbane and Women's Hospital and the other by lights and sirens to the Sunshine Coast University Hospital.

Authorities said at about 2pm they expected the bridge to be closed to the public for the next two to three hours.

Locals and commuters stuck in the delays took to social media.

"We're waiting for traffic, it's virtually a car park" one commenter said.

"All traffic getting turned away from bridge on Bribie side" another posted.

The fire was reportedly put out just before 1pm.