Fire crews rushed to the scene in Seabegs Road, which connects the village and Bonnybridge, to tackle the flames which could be seen engulfing the lower level of the First Bus vehicle.
Fortunately, the operator has confirmed no one was injured during the blaze on board the X37 service, the cause of which is not yet known.
Eyewitness Graeme Bell (32), who lives in Allandale, said: “I was out my back garden and I heard a loud banging noise as if a tractor had steel beams attached to the wheels and then I saw the bus.
“It was an engine problem by the sounds of it. Luckily there wasn’t anybody hurt.”
First Bus has credited the quick-thinking of the driver of the double decker, who spotted the danger in enough time to pull over and allow four people on board to get off.
A First Scotland East spokesman said: “We can confirm our vehicle was involved in an incident at 8.05pm last night (August 20) in Allandale. No passengers or staff were injured in any way in the incident.
“The driver deserves huge praise as his swift actions to stop the vehicle and evacuate all four passengers have prevented any injuries whatsoever and avoided a much more serious incident.
“Our staff are all highly trained and we have emergency procedures in place for this sort of incident.
“Passenger and staff safety is our number one priority and is at the forefront of everything that we do. We will now carry out a full internal investigation to establish the root cause.”
Firefighters spent close to an hour extinguishing the blaze.
A fire service spokeswoman said: “The Scottish Fire and Rescue Service was alerted at 8.05pm on Monday, August 20 to reports of a bus on fire in Bonnybridge.
“Operations Control mobilised two fire engines to Seabegs Road, Allandale where firefighters extinguished the fire.
“There were no casualties. Crews left the scene at 9.33pm after ensuring the area was made safe.”