Fire broke out at a 250 MW unit of Tata Power's thermal plant at Trombay and the company said that the reasons for "the event" as well as the damages would be ascertained in "due course".
Power generation from rest of the units remain unaffected by the incident. The project has an operational capacity of 1,580 MW.
The company today said its Trombay thermal power plant had a localised incident of fire late last night.
"At 11.11 pm, a loud thud notice was observed in Low Pressure Turbine accompanied by fire on the turbine and generator deck of the 250 MW Unit 8 at Trombay.
"The plant was safely shutdown including safe purging of hydrogen from the generator and safe shutdown of boiler, as the unit was running with about 185 MW capacity," the statement said.
Alternate supply is being maintained to meet the electricity demands of Mumbai consumers.
According to the statement, the extent of damage and reasons for the event shall be ascertained in due course with engineers of Tata Power and Original Equipment Manufacturer experts from BHEL.
"No casualty has occurred nor is any human involved in the event associated with the key plant and equipment," it added.
In November, the company's 4,000 MW Mundra ultra mega power project in Gujarat had witnessed a fire incident.
Tata Power has generation capacity of more than 8,500 MW.