A Hazmat incident at a Bee-Line Bus Garage in Valhalla led to an evacuation from the facility on Monday.
Officials say several people experienced burning eyes and had to run out of a building located at 5 Walker Road.
A 911 call came in around 6 p.m., with reports of fog coming from the building. The building was then evacuated.
Officials believe it was caused by routine disposal of expired tear gas containers at the Westchester County Police Academy's Special Operations division.
They say the cold weather may have led the gas to travel to the garage rather than fade into the atmosphere.
A total of 15 people were treated for irritated eyes. One person went to the hospital for minor injuries.