The Spokane, Washington, Fire Department called HAZMAT crews to assist after a worker mixed incompatible chemicals at the Courtyard by Marriot Spokane Downtown.

Although the initial report indicated mustard gas, the Washington Department of Ecology clarified it was actually the potentially lethal chlorine gas, which was produced by accidentally mixing muriatic acid with liquid chlorine.

The Spokane Fire Department monitored the gas concentration in the air and evacuated the area near the swimming pool facility as a precaution. HAZMAT crews were then sent in to neutralize the reaction and dispose of the product.

The incident occurred at around 4 p.m. on March 28, and crews began to wrap up before 9 p.m. No injuries were reported.