No injuries were reported in the blaze that broke out around 9.15 am on the bus plying on route 138 in the Fort area near the Chhatrapati Shivaji Maharaj Terminus, they said.

This is the first incident of fire involving double-decker electric buses inducted in the BEST fleet in the last three years.

A fire engine was rushed to the spot, and the blaze was doused immediately, a fire official said.

The affected bus had departed from Bhatia Baug next to CSMT and was heading to the Backbay Depot, a BEST spokesperson said.

“The blaze erupted near a high-voltage battery located next to the front left tyre,” he said.

The bus was packed at the time of the incident, but the driver steered it to the side as soon as he noticed the fire, and passengers alighted safely, he said.

SVR Srinivas, BEST General Manager, told PTI that as per preliminary investigation, the fire may have been triggered by the brushing of the underbelly battery packs of the bus with the iron cover of the manhole on DN Road.

BEST officials have noticed some damage marks on the battery pack cover, he said, adding that further probe is underway.

The Mumbai Metro Rail Corporation Limited (MMRCL), which is constructing the city’s first underground metro corridor, recently resurfaced the section of DN Road where the incident happened.

According to the spokesperson, the double-decker bus is one of the 50 buses that the public transport body has taken on lease from Switch Mobility, a subsidiary of automobile manufacturer Ashok Layland.

Videos of the incident that surfaced on social media showed the bus surrounded by thick white smoke before the fire started from the underframe batteries of the vehicle.

Passengers, including women, can be seen jumping out of both doors of the bus even as passersby and a civic staffer shout instructions about vacating the vehicle. PTI KK GK ARU