During the night of the leak, water somehow entered a large tank of methyl isocyanate and set off a chemical reaction that quickly raised the mixture's temperature. Safety valves failed and the poisonous cloud poured out into the nearby neighborhoods. People woke up in the middle of the night with burning eyes and gasping for breath. Many died in their beds; more died in the mad rush to flee. Many questions were raised in the aftermath and it emerged during various lawsuits that Union Carbide had failed to create action plans to cope with accidents, had failed to install and maintain proper backup systems, had not kept the chemical tanks at the proper temperature and in general was lacks on safety.
Twenty-five years after the spill, the effects are still being felt by the people of Bhopal. More than 390 tons of chemicals lay abandoned at the shuttered Union Carbide plant and are being blamed for a high rate of cancer, birth defects and other health problems in the surrounding area. Indian courts issued a warrant for the arrest of former Union Carbide chief executive Warren Anderson and ordered India's government to press the U.S. government for his extradition. The disaster is now showing effects in multiple generations — the children of survivors of the chemical leak are starting to have children with severe rates of defects and abnormalities.