Nearly half of India was left without power today after the nation's northern and eastern electricity grids failed.
The collapse of the grids came a day after the northern grid failed and left eight states without power for much of the day.
Shailendre Dubey, of Uttar Pradesh Power Corp in India's largest state, said the northern grid collapsed at about 1.05pm local time.
SK Mohanty, a power official in the eastern state of Orissa, said the blackout in the eastern grid was triggered by a fault and could take several hours to resolve.
The two grids serve about half India's population - some 600 million people.
The power failures have raised concerns about India's outdated infrastructure and its insatiable appetite for energy that the government has been unable to meet.