A major electricity supply failure in the Mumbai Metropolitan Region (MMR) has led to a power outage all over Mumbai city. The Brihanmumbai Electricity Supply and Transport (BEST) which is responsible for supplying power to the city has confirmed the development. Maharashtra power minister Nitin Raut said An inquiry will be done on what led to power failure. Maintenance of Kalwa Padgha Line 1 was underway when the load increased on Line 2 which tripped leading to power failure. Watch the video.