Philadelphia's major electric company lost power at its downtown headquarters, leading to a building-wide evacuation.
Fire Capt. Jeffrey Thompson says firefighters responding to the PECO building on Wednesday found that a transformer had malfunctioned.
A spokesperson for PECO did not immediately respond to a request for comment.
PECO serves 1.6 million electric and 486,000 natural gas customers in southeastern Pennsylvania. It is a subsidiary of Exelon Corp.
Copyright AP - Associated Press