The outages in 21 of India's 28 states each lasted hours following the collapse of major electricity grids. The blackouts disrupted essential services, jammed vehicular traffic in already crowded cites, including New Delhi, stranded people and trapped about 200 miners underground near the eastern city of Kolkata.
Critics and opposition party leaders blasted the federal government and some state officials for not taking timely action.
"Powerless & Clueless," said the front-page headline in the Times of India, which reported: "It was a terrible Tuesday that 684 million Indians are not going to forget in a hurry."
Authorities Wednesday said power had been restored in the affected regions.
The BBC quoted the head of the state-owned power system as saying electricity had been restored in all three affected grids overnight.
People, however, began stocking up on essential supplies, fearing another outage.
Power shortage has been a perennial problem in the country.
Indian Power Minister Sushil Kumar Shinde, whose appointment as the country's home minister in a Cabinet reshuffle came on the day of the crisis, said some states had been exceeding their power quotas.
"This situation is a grim reminder of the humongous task we have on our hands in improving the infrastructure facilities in the country," R.V. Kanoria, president of the Federation of Indian Chambers of Commerce and Industry, said in a statement.
One welcome development coming out of the disaster was the government's decision to extend the deadline for submitting income tax returns for some filers from July 31 to Aug. 31, the Times reported.