The wet leased midi bus involved in the accident was hired from Olectra Greentech.

Under the wet lease model adopted by BEST, contactor or operator bears fuel, driver and maintenance cost of the bus, he explained.

As per primary information, the BEST undertaking's own driver was behind the wheel at the time of the crash, the official said.

Earlier this year, mini buses, which were being operated on crowded routes connecting Bhandup station in eastern suburbs to slum-dominated areas close to foothills of Sanjay Gandhi National Park, were withdrawn from BEST fleet.

Despite operational constraints like inadequate turning radius, BEST, facing shortage of buses, introduced Olectra-made midi buses on routes from Bhandup (West) station, the official said.

BEST operates a large fleet of buses, covering the city and its neighbouring urban areas.

Mumbai Congress president and Lok Sabha MP Varsha Gaikwad sought an inquiry into the accident.

"This is extremely saddening. Faulty buses, untrained drivers and an administration unwilling to invest in and improve BEST are risking several lives on a daily basis. We demand a thorough inquiry into this incident," said Gaikwad.