The U.S. Chemical Safety Board says it will investigate a chemical spill in the Elk River that has contaminated the public water supply in nine counties.
Board chairman Rafael Moure-Eraso said Saturday that the board wants to find out how a leak of such magnitude occurred, and how to prevent similar incidents in the future.
U.S. Sen. Jay Rockefeller says he's pleased with the board's quick response to his request for an investigation.
Thursday's spill from a Freedom Industries facility in Charleston also is being investigated by the U.S. Attorney's Office and the U.S. Occupational and Safety Administration.
West Virginia American Water has told 300,000 people in the affected counties to not drink their tap water or use it for bathing, cooking and washing clothes.