Two people were killed, and more than 20 others were injured on Wednesday after a toxic gas release at a chemical facility in Institute, West Virginia, prompting a large-scale emergency response and a temporary shelter-in-place order in the surrounding area.

The incident occurred around 9:31 a.m. at Catalyst Refiners, Inc., located in Kanawha County near Charleston, as the plant was undergoing shutdown procedures. Officials said workers were conducting cleaning and decontamination operations when a chemical reaction produced hydrogen sulfide, a highly toxic gas.

According to county authorities, the reaction involved nitric acid and another substance, leading to what officials described as a sudden and severe chemical event. Kanawha County Commissioner Lance Wheeler Sigman said the reaction escalated rapidly during the process.

Emergency officials confirmed two fatalities at the site, though the identities of the victims have not been released. At least 21 individuals sought medical attention following exposure, with some transported by ambulance and others arriving at hospitals by private vehicle. One patient was reported in critical condition.

First responders were also evaluated after possible exposure while assisting at the scene. West Virginia Gov. Patrick Morrisey said state officials are monitoring the situation and expressed concern for those affected, including emergency personnel.

The incident triggered a large decontamination effort, with exposed individuals required to remove contaminated clothing and undergo on-site cleansing procedures. Officials said the odor associated with the gas remained concentrated near the facility.

Local hospitals reported treating patients for respiratory symptoms, including coughing, shortness of breath, sore throat, and eye irritation.

Authorities issued a shelter-in-place order for nearby residents, which remained in effect for more than five hours before being lifted once conditions stabilized.

The company said it is cooperating with investigators. Federal workplace safety officials, including the Occupational Safety and Health Administration, are expected to review the incident as part of an ongoing investigation.