The vehicle caught fire at the Monge-Mutualité stop, on rue des Ecoles, with witnesses hearing two loud explosions.
Its shocked driver raised the alarm after he noticed smoke belching from the vehicle.t
He quickly brought the bus to a stop and evacuated the bus of all its 30 passengers.
Everyone escaped without injury but the bus was completely destroyed by the flames.
Police had to cordon off the road as it filled with filthy smoke.
Photos from the scene showed the charred wreckage cordoned off at the side of the busy road.
The driver was later congratulated by mayor of the 5th arrondissement Florence Berthout and praised for his “cool head” under pressure.
But she demanded to know how the fire, which started at around 9am local time, had spread so quickly, engulfing the whole vehicle and wrecking it.
She tweeted: “An investigation must be carried out immediately to determine the reasons for this accident.
“It could have had very serious consequences.”