More than half of India’s 1.2 billion population are without power in the country’s second blackout in as many days.
Road and rail networks shut down and hospitals switched to backup generators.
India’s Power Minister Sushilkumar Shinde vowed to fix the problem as soon as possible.
“I have put all my people on the job. The power grid chairman is working. Now we are getting power from the western region and other places,” he told reporters.
The government blamed the outage on some states drawing too much power from an already overstretched electricity grid.
On Tuesday evening, there were some 20 states affected across northern and eastern India.
The transport systems ground to a halt in those parts of the country.
In Delhi, the metro and trains were evacuated. A full service is not expected for several hours.