KANSAS CITY, Mo. (AP) — Three people were sickened by carbon monoxide at a Kansas City office building.

Firefighters responded to a call about noon Monday regarding shortness of breath at an office building in the Crossroads Art District. Firefighters found high levels of carbon monoxide at the site. Firefighters measured the concentration of carbon monoxide at about 1,300 parts per million, about 26 times higher than the danger threshold.

Kansas City Fire Department Battalion Chief James Garrett says one person was critical, a second person was non-critical and a third person got their own medical treatment.

Garrett says firefighters determined that power equipment being used in the building’s basement created the carbon monoxide. Firefighters shut off the equipment and ordered an evacuation.