Two residents and an employee were killed and about 20 people injured, including one of the utility workers, just a few days before Christmas. Part of the building collapsed, trapping people inside, as emergency workers, staff and even medics from a nearby hospital rushed to evacuate people. Exelon, PECO’s parent company, shut off the gas flow to the facility almost two hours after the explosion, according to the report. The Exelon energy technician determined there was a leak on a meter set valve in the basement and called for help fixing it. A meter set includes the meter, regulator, piping, valves and fittings.