Commuters wait Monday for a metro train in New Delhi, India. Northern India's power grid crashed Monday, halting hundreds of trains, forcing hospitals and airports to use backup generators and leaving 620 million people sweltering in the summer heat. It's one of the world's biggest-ever blackouts.

NEW DELHI — India’s energy crisis cascaded over half the country today when three of its regional grids collapsed, leaving 620 million people without government-supplied electricity in one of the world’s biggest-ever blackouts.

Hundreds of trains stalled across the country and traffic lights went out, causing widespread traffic jams in New Delhi. Electric crematoria stopped operating, some with bodies half burnt, power officials said. Emergency workers rushed generators to coal mines to rescue miners trapped underground.

The massive failure — a day after a similar, but smaller power failure — has raised serious concerns about India’s outdated infrastructure and the government’s inability to meet its huge appetite for energy as the country aspires to become a regional economic superpower.

Power Minister Sushil Kumar Shinde blamed the new crisis on states taking more than their allotted share of electricity.

“Everyone overdraws from the grid. Just this morning I held a meeting with power officials from the states and I gave directions that states that overdraw should be punished. We have given instructions that their power supply could be cut,” he told reporters.

The new power failure affected people across 20 of India’s 28 states — more than the entire population of the European Union plus Turkey.