At about 3:45 Wednesday afternoon, Chester County’s Department of Emergency Services reported that a PECO transformer was on fire underground at 200 West Gay Street. A separate fire underground was also reported at North Darlington Street and Courthouse Alley. Crews reported smoke in the building. Twelve firefighters were overcome by carbon monoxide, with four taken to Chester County Hospital and 8 treated on the scene. One of those firefighters is in serious condition with a cardiac arrest. Local restaurants were evacuated and also the Chester County Justice Center. We will continue to update you as we receive more information on this breaking news story.