An electric air-conditioned bus of the civic-run Brihanmumbai Electric Supply and Transport (BEST) caught fire while parked in a depot in suburban Malvani on Friday afternoon, an official said.
Nobody was injured in the incident.
The fire started around 2.55 pm on the rooftop of the single decker e-bus manufactured by Tata Motors, said a BEST spokesperson.
"The fire brigade was called immediately and the fire was doused," he added.
The bus, hired from a private contractor, had completed a 53 km run since Friday morning on route no 359 and arrived at the depot around 1 pm, the spokesperson said.
"Officials are investigating the cause of the fire," he added.
A civic official said the fire started in the AC unit installed on the roof of the bus. As the bus was empty, nobody was injured, he added.
In a statement Tata Motors confirmed the incident.
"We have taken immediate action and will closely work with the local authorities to identify the cause and accordingly take remedial actions," the firm's spokesperson said.