Authorities have declared a state of emergency and a ban on tap water for nearly 300,000 people in nine counties, after a chemical spill contaminated a water-treatment facility on the Elk River in West Virginia, resulting in the closure of schools and restaurants in the region.

Governor Earl Ray Tomblin tweeted on Thursday, warning consumers against using tap water. The chemical 4-Methylcyclohexane Methanol, used in the coal industry, leaked from a tank at Freedom Industries located along the Elk River in Charleston. The leak reportedly contaminated a West Virginia American Water Company's treatment facility near the chemical plant, affecting tens of thousands of people.

"West Virginians in the affected service areas are urged NOT to use tap water for drinking, cooking, washing or bathing," Tomblin said in a statement. "Right now, our priorities are our hospitals, nursing homes, and schools.

"I’ve been working with our National Guard and Office of Emergency Services in an effort to provide water and supplies through the county emergency services offices as quickly as possible.”

The countries affected are Kanawha, Boone, Cabell, Clay, Jackson, Lincoln, Logan, Putnam and Roane, and health officials said the water should be used only for flushing toilets and fighting fires. It is not clear how much of the chemical leaked from the 48,000-gallon storage tank, and how long it would take to clean up the facility.

“All we know is that they discovered a hole in the tank, and material was leaking,” Tom Aluise, a spokesman for the state's department of environmental protection, told the Los Angeles Times. “How that hole got there, we don’t know.”

The leak was detected after customers complained about a black licorice-like odor emanating from the tap water. However, officials said they are not sure how hazardous the contamination is.

"I don't have anything to indicate the water is not safe. It's an abundance of caution that we're taking this step. We don't do this lightly, tell our customers not to use the water," Jeff McIntyr, president of the water company, told Fox News.

According to chemicalbook.com, the chemical is explosive when dry, and is toxic when swallowed. It can cause severe burns, irritation to the eyes, skin and respiratory system. However, authorities said that the chemical was diluted by the time it reached the water treatment plant, and no reports of sickness have been reported so far from the affected region.

The tap-water ban resulted in chaos in the region with customers queuing up at convenience stores to buy packaged water, and most stores were soon reportedly forced to hang “We are out of water” signs.