India, the country home to the world’s second largest population of 1.2 billion, is in the midst of what’s possibly the largest electrical failure in history. More than 600 million people are without power throughout 11 provinces in the Indian north and east.

India’s power minister hasn’t specified the root cause of the problem, though he says there are problems with the country’s power grid. Some are speculating that states are using more power than the grid can handle, causing the outage.

The country experienced its first major outages Monday, which affected upwards of 350 million people — more than the entire U.S. population. New Dehli, the capital city whose metro area is home to more than 20 million people, was left in the dark by both power failures. According to Indian Railways, at least 300 trains have been canceled due to the outages.