Fairfax County Fire and Rescue Department units responded to a medical emergency early this morning in the Bailey’s Crossroads area of Fairfax County. Upon arrival, firefighters found three occupants with potential symptoms of carbon monoxide poisoning.

Using meters, firefighters found high levels of carbon monoxide in the apartment. One adult female and one adult male were treated and then transported to INOVA Fairfax Hospital, and one adult male was transported to Arlington Hospital, all for life-threatening injuries.

The building, an 11-unit, three-story, garden apartment on Malibu Circle, was immediately evacuated with occupants being able to reenter approximately four hours later after firefighters ventilated the structure.

Firefighters and gas company officials determined the cause of the carbon monoxide to be a faulty furnace in the apartment of origin.