The Upper Big Branch Mine disaster occurred on April 5, 2010 roughly 1,000 feet (300 m) underground in Raleigh County, West Virginia at Massey Energy's Upper Big Branch coal mine located in Montcoal. Twenty-nine out of thirty-one miners at the site were killed. The explosion occurred at 3:27 pm. The accident was the worst in the United States since 1970, when 38 miners were killed at Finley Coal Company's No. 15 and 16 mines in Hyden, Kentucky.