Maharashtra Chief Minister Uddhav Thackeray on Monday ordered an immediate investigation into a major grid failure that caused widespread power outage in Mumbai, which led to the suspension of suburban train services and brought India’s financial capital to a halt, PTI reported.

Tata Power said it has restored power supply to Mumbai fully after starting the process at 12 pm. Many homes were without electricity from 10 am. Mumbai’s international airport and the country’s two main stock exchanges located in the city, the National Stock Exchange and the Bombay Stock Exchange, were functioning normally despite the outage.

However, The Indian Express reported that efforts are still underway to resume supply in other affected locations.

State Energy Minister Nitin Raut also said the reason behind the technical snag would be investigated. An official statement said Thackeray took “serious note” of the power outage. The chief minister also instructed Brihanmumbai Municipal Corporation Commissioner Iqbal Singh Chahal to make alternate arrangements so that the power supply to hospitals is intact, many of which are treating coronavirus patients.

The exact reason for the power outage is not yet clear, but the Western Railway and the Brihanmumbai Electric Supply and Transport, the state-run discom supplying power to the city, blamed Tata Power. Initially, multiple trippings of power lines was cited as a reason for the massive outage. Juhu, Andheri, Mira Road, Navi Mumbai, Thane and Panvel were among the areas that were majorly affected.

Adani Power Limited, another major power suppliers to the city, said it was supplying around 385 megawatts to critical services through its Dahanu power station.

Train services were also fully restored on both Central and Western Railway. Central Railway trains were restored at 10.55 am, according to NDTV.

Social media was filled with pictures of people stranded inside unlit trains and in railway stations. Others also took to complain about the sudden outage.