INSTITUTE, W.Va. (AP) — A chemical leak at a West Virginia silver recovery business on Wednesday killed two people and sent 19 others to the hospital, including one in critical condition, authorities said. The leak occurred at the Catalyst Refiners plant in Institute as workers were preparing to shut down at least part of the facility, Kanawha County Commission Emergency Management Director C.W. Sigman said.

A chemical gas reaction occurred at the plant involving nitric acid and another substance, Sigman said, speaking at a news briefing. He added that there was 'a violent reaction of the chemicals and it instantaneously overreacted.' Sigman noted that starting or ending a chemical reaction are the most dangerous times.

Among the injured were seven ambulance workers responding to the leak, officials said. Other people were taken to the hospitals in private cars or even in one case a garbage truck, Sigman said. One person was in critical condition, Kanawha County Commission President Ben Salango said.

Vandalia Health Charleston Area Medical Center, one of several hospitals in the area, treated multiple patients, some brought by ambulance, while community members were arriving inquires about check-ups.

WVU Medicine Thomas Memorial Hospital in South Charleston reported taking in a dozen patients, including eight who were not at the scene but were nearby at the time. None were considered life-threatening injuries.

A shelter-in-place order was issued for the surrounding area and was lifted after more than five hours. Officials emphasized that all casualties occurred on the plant site, with Sigman stating that one had to be close to the facility to detect the leak's smell.

The leak necessitated a large-scale decontamination operation, requiring individuals to disrobe and be sprayed down. Catalyst Refiners specializes in recovering silver from chemical processes, retrieving precious metals in various forms.

Ames Goldsmith Corp., the plant's owner, expressed sadness over the fatalities and promised to assist local, state, and federal officials during the investigation. The plant is located in a historically hazardous area, known as West Virginia's 'chemical valley', which has seen many factories come and go due to changing standards and ownership over the decades.