The resulting hazardous materials emergency prompted an immediate and widespread response from first responders, including hazmat crews and the Oklahoma National Guard, to contain the colorless but dangerous gas.
A tanker truck leaking anhydrous ammonia gas in the parking lot of a local hotel triggered a major hazardous materials emergency in the city of Weatherford, Oklahoma, on Wednesday night, leading to the hospitalization of dozens of people and forcing hundreds more to evacuate their homes.
The incident began shortly before 10 p.m. Wednesday when the tanker truck, parked behind a Holiday Inn Express, started billowing the dangerous gas. Police Chief Angelo Orefice indicated the cause appeared to be a mechanical failure, possibly a faulty seal or valve on the truck, which was carrying 25,000 pounds of the chemical.
The tanker truck was identified as belonging to industrial gas distributor Airgas. Anhydrous ammonia is a common farm fertilizer but is a colorless gas with a pungent, suffocating odor that can be deadly at high concentrations and causes severe breathing problems and burns.
The resulting plume of gas immediately caused those in the vicinity, including guests at the hotel, to suffer from respiratory distress. Emergency workers, donning gas masks, went door-to-door in affected residential areas in the early hours of Thursday morning, waking people and urging them to evacuate. The swift action displaced an estimated 500 to 600 people, who were directed to a shelter. Several nursing homes were also evacuated, and schools across the district were closed for the day as a precaution.
In total, 36 people were treated at the emergency room of Weatherford Regional Hospital for exposure. While most were treated and released, 10 patients were transferred to hospitals in the Oklahoma City area for further care, with officials noting that several were initially in critical condition. In addition, five responding officers sustained chemical burns to their airways during the initial response efforts.
By Thursday morning, officials lifted a shelter-in-place order that had been in effect for several hours, confirming that the leak had been controlled. The Environmental Protection Agency (EPA) confirmed that subsequent air monitoring did not detect any ammonia in the local residential area, and the pH levels in the local creek were within normal limits.
However, the cleanup effort for the 12,000-person city, located about 70 miles west of Oklahoma City, is expected to be a multi-day operation. Police Chief Orefice stated that authorities were working with environmental officials to manage the site, noting that much of the hazardous material had been "diluted." Airgas released a statement confirming its cooperation with local authorities and emphasizing the necessity of cautious handling for anhydrous ammonia.
