A massive power cut blacked out a vast swathe of northern India on Monday, leaving more than 300 million people without power in the worst outage in over a decade, officials said. Power Minister Sushilkumar Shinde said the entire northern grid collapsed for six hours shortly after 2am (2030 GMT Sunday), causing chaos in nine states including the capital New Delhi. The cut severely disrupted transport networks, stranding several hundred trains, which required the deployment of diesel engines to pull them to safety, railways officials said. In New Delhi, metro services started up an hour late and were operating at only 25 percent capacity for most of the morning, while traffic lights also went down causing snarls in the early rush hour. Major hospitals and airports in the region were able to function normally on emergency back-up power, officials said. “We are used to electricity going occasionally, so we have a good back-up system,” said a spokesman for Safdarjang Hospital in New Delhi. The New Delhi water board said the capital’s seven water treatment plants were shut down by the blackout, but five were back in operation by mid-morning. The northern grid covers a vast region that is home to 28 percent of India’s 1.2 billion population, and includes the states of Jammu and Kashmir, Punjab, Rajasthan and Uttar Pradesh. “It is an accident, a failure,” Shinde told reporters, adding that a special committee was being set up to probe the precise trigger for the blackout. According to the Power System Operation Corp (PSOC), which manages the northern grid, 100 percent power had been restored to New Delhi as of 1pm and 70 percent to the rest of the affected region. Limited power outages are extremely common across India, which runs a peak-hour power deficit of around 12 percent according to the Central Electricity Authority. Industry leaders say electricity shortages have become a major obstacle to economic growth in the country, which has an installed power generation capacity of 187 gigawatts – about 20 percent of China’s level. “I believe it (the outage) could be because of the great indiscipline of the states in overdrawing power – the grid will only collapse if you overdraw,” said Vivek Pandit, energy director at business lobby group the Federation of Indian Chambers of Commerce and Industry. Shinde said the speed with which the situation had been remedied compared well with similar mass outages in the developed world, including the 2003 blackout that affected much of the eastern seaboard of the United States. “It took four days to restore power in America… our power grid is very good,” he said. Within hours of the northern region going down, electricity was brought in from the eastern and western grids, as well as the neighbouring Himalayan kingdom of Bhutan.