Power supply in northern states was severely affected on Monday with the failure of Northern Grid at about 2:30 am.
The states affected are Delhi, Punjab, Haryana, UP, Himachal and Rajasthan.
"Yes, there are problems with Northern Grid, we are trying to restore it," said SK Soonee, CEO of Power System Operating Co (PSOC)
PSOC manages the Northern Power Grid.
Officials sources said while the exact reasons for the grid failure are being ascertained, over drawl of power by states could have led to the problem.
The restoration of the grid may take a few more hours even as the engineers are trying to restore it since early morning.
Power supply in some pockets is being restored and the first priority is for public services like hospitals and transport.
"We are hoping to restore the grid in the next one or two hours. We are giving essential loads for services like Railways, Metro and Hospitals," Chairman and Managing Director of Power Grid Corporation AM Nayak said.