The Ontario Ministry of Labour is investigating a chemical spill at the Hilton Hotel complex in Niagara Falls on Fallsview Blvd.
Police and emergency services personnel were dispatched Saturday evening after staff reported the spill in the basement of the hotel's middle tower
Niagara Regional Police said approximately 160 hotel rooms, as well as some shops and restaurants, were evacuated as a precaution until a hazardous materials team gave the all clear about an hour later.
They said city transit buses were provided to shelter the evacuees.
Two hotel employees were taken to hospital, one of whom was later released, and there was no immediate word on the condition of the other.
Police didn't reveal the type of chemical involved, but said the incident was not being treated as a criminal matter.