Power has been restored to large parts of India's financial capital Mumbai after a rare outage, officials say.
The city's suburban train network came to a halt and homes lost electricity supply around 10:00 local time on Monday (04:30 GMT).
Officials said the "unprecedented failure" was because of issues with "incoming supply to the main grid".
While power cuts are common in large parts of India, they are rare in major cities, and especially in Mumbai.
The chief minister of Maharashtra state, where Mumbai is located, has ordered an inquiry into the cause of the power failure.
"Supply has since been restored to all essential services in large parts of the city," the state's energy minister, Nitin Raut, said in a tweet.
But the outage is unusual enough that residents quickly took to social media, wondering when was the last time they had faced a power cut that lasted longer than a few minutes.
Some even questioned officials for not being prepared to quickly resolve such a massive outage.
While the grid failure interrupted trains, the airport and the stock exchange continued functioning.
Officials have asked hospitals to ensure they have enough fuel to power back-up generators for at least eight hours in case of further disruptions. Most hospitals are equipped to run on generators.
Mumbai is one of the busiest cities in the world and has been reopening slowly while battling one of the country's highest Covid-19 caseloads.
This is not the first time a major Indian city has witnessed interruptions in power supply. A failure in the main grid disrupted power supply across the country in 2012.