MUMBAI (REUTERS) - A grid failure caused a widespread power outage in India's financial capital Mumbai and surrounding areas on Monday (Oct 12), the authorities said, a rare occurrence that disrupted train services in the city of 20 million.

"Power cut across the Mumbai Metropolitan Region due to grid failure," the Brihanmumbai Electric Supply and Transport agency said on Twitter.

A government official in Mumbai said other power suppliers such as Adani Power and Tata Power had also been affected by the outage. The companies could not immediately be contacted for comment.

India's two main stock exchanges, the National Stock Exchange and BSE, as well Mumbai's international airport, said they were operating normally.