A Kitchener high-rise was evacuated Sunday due to a carbon monoxide leak.

The leak was discovered around 4 p.m. at a 19-storey apartment building on Cedarwoods Crescent, off of Kingsway Drive.

Officials said they found high levels of carbon monoxide on the 11th floor of the building.

A total of 21 firefighters were called to the scene. Six of them were treated for symptoms of carbon monoxide poisoning, with two requiring hospitalization.

By late Monday morning, both firefighters had been discharged from hospital.

Grand River Transit buses were brought in to keep the building’s residents warm while the leak was dealt with.

Everyone was allowed back inside around 7 p.m.