The bus was moving on Kona Expressway when flames were noticed in the front part of the bus, following which passengers were asked to disembark, police said.
The fire was put off shortly afterwards.
The cause of the fire is yet to be known, police said, adding that it could be due to some technical glitch.
Months back an AC bus on Satragachi-Barasat route had also caught fire on Vidyasagar Setu and then too all passengers were miraculously saved.
