Half of India was thrown into darkness on Tuesday, as North, East and North-East India entered its second consecutive day of a mass blackout, triggering a major power crisis across the country.

After two days of power outage, the nation returned to normalcy as electricity supply was finally restored in three grids connecting 20 states. "Power has been restored fully across the northern, eastern and north-eastern grids," Power System Operation Corporation (PSOC) chief SK Soonee said on Wednesday.

PSOC engineers worked overnight to restore the multiple-grid failure that occurred on Tuesday afternoon in one of the worst power failures of the past decade.

The crisis, which began on Monday after power grid failure was reported in the Northern region, spread to the Eastern and North-Eastern states the following day.

The Northern Grid covers nine states including Delhi, Punjab, Jammu and Kashmir, Himachal Pradesh, Haryana, Uttar Pradesh, Rajasthan, Chandigarh and Uttarakhand. The Eastern Grid and North-eastern Grid covers states including West Bengal, Odisha, Jharkhand, Bihar, Sikkim, Assam, Mizoram, Manipur, Tripura, Nagaland, Meghalaya and Arunachal Pradesh.

The outage affected as many as 600 million people while disrupting public transportation, hospital operations and leaving hundreds of coal miners trapped underground. Crippled by the sweltering heat in the national capital, people rushed to shopping malls, which were kept air-conditioned by generators.  Water woes in Delhi increased as with several other perishable items that were left rotting amid scorching temperatures.

Meanwhile, the government will begin an investigation into the cause of the grid failure. Officials have blamed overdrawing of power by certain states as reason for the power failure.   

Below are a series of photos showing how the nation dealt with the world's worst blackout for the past two days:

Blackouts in India
Muslim girls study in the light of candles inside a madrasa or religious school during power-cut in Noida on the outskirts of New Delhi (Reuters)
Blackouts in India
An electric pylon carrying high tension wires is pictured in front of a residential complex after electricity was restored in New Delhi (Reuters)
Blackouts in India
Traffic moves along a busy road after electricity was restored in New Delhi (Reuters)
Blackouts in India
A shopkeeper watches a screen as he waits for customers at his illuminated shop after the electricity was restored in New Delhi (Reuters)
Blackouts in India
A man walks on an illuminated street after electricity was restored in New Delhi (Reuters)
Blackouts in India
An illuminated stretch of a residential complex is pictured after electricity was restored in New Delhi (Reuters)
Blackouts in India
A shopkeeper interacts with a customer at his illuminated shop after electricity was restored in New Delhi (Reuters)
Blackouts in India
Heavy traffic moves along a busy road during a power-cut at the traffic light junctions in New Delhi (Reuters)
Blackouts in India
Passengers rest on a platform for their train to arrive as they wait for electricity to be restored at a railway station in New Delhi (Reuters)
Blackouts in India
Passengers sit on a platform for their train to arrive as they wait for electricity to be restored at a railway station in New Delhi (Reuters)
Blackouts in India
Passengers sit in a train as they wait for electricity to be restored at a railway station in New Delhi (Reuters)
Blackouts in India
An officer reads documents with the help of a torch at the driving registration and license authority office during a power-cut in Chandigarh (Reuters)
Blackouts in India
People stand inside the driving registration and license authority office during a power-cut in Chandigarh (Reuters)
Blackouts in India
Employees manually fill containers with diesel during a power cut at a fuel station in New Delhi (Reuters)