The Northern and Eastern Grids tripped on Tuesday, leading to power failure in several states of the country affecting hundreds of millions of people.

While the Northern Grid collapsed for the second time in two days, the Eastern transmission lines too failed this afternoon, said officials at the Power Ministry and electricity companies.

Power supply was disrupted in Delhi, Uttar Pradesh, Haryana, West Bengal, Assam and Punjab, among other states.

"Yes, I've heard that the Northern and Eastern grids have failed. We are looking into the matter. We are inquiring," Power Minister Sushilkumar Shinde said.

The power crisis led to immediate shut-down of Delhi Metro lines in the national capital, while a host of other services including Railways were also affected.

"We are again having problems in Northern Grid," K Soonee, CEO of Power System Operating Co (PSOC) said.

Power Ministry officials said that Eastern Grid has also failed. The reasons for the grid failure were not immediately known.

While an almost 15-hour power crisis was seen in the Northern part yesterday, the crisis today reached the Eastern region as well.

Delhi government officials said the Northern Grid failed at around 1:30 PM, when the national capital had a demand of around 4,000 MW. Only 38 MW was being supplied at around 1:45 PM.