CHARLESTON, W.Va. — The U.S. attorney in West Virginia said this morning that federal authorities are opening an investigation into what caused a chemical spill that tainted a river and shut down much of the state’s capital city and surrounding counties.

U.S. Attorney Booth Goodwin said in a news release that his office and other agencies will investigate the circumstances surrounding the release and determine what caused it. He says authorities will take whatever action is appropriate based on the evidence found.

The chemical, used in coal processing, spilled from a Freedom Industries plant into the Elk River in Charleston. Officials have ordered people not to drink, cook with or bathe in tap water, forcing people to scramble for bottled water.

How much of the chemical spill, and the extent of the danger, remains unclear.