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A young Indian boy watches from a window of a stalled train as he waits for the train to resume its services following a power outage at a railway station in New Delhi, India, Tuesday, July 31, 2012. India's energy crisis cascaded over half the country Tuesday when three of its regional grids collapsed, leaving 620 million people without government-supplied electricity for several hours in, by far, the world's biggest blackout. Hundreds of trains stalled across the country and traffic lights went out, causing widespread traffic jams in New Delhi. (AP Photo/Kevin Frayer)

Blackout in India

Half of India's 1.2 billion people were without power on July 31 as the grids covering a dozen states broke down. More than 600 million people were left without power in one of the world's biggest-ever blackouts.