Work is ongoing to find the cause of a gas explosion that rocked an outbuilding of the Quad Cities nuclear power plant early on 27 October. Owner Exelon said in an emailed statement that the plant's reactors operated normally at full power throughout, but that an explosion had occurred in the vestibule of an outbuilding which housed a tank and pump to store liquids drained from the plant floor. Exelon noted no casualties and no damage to equipment, but reported the incident to the Nuclear Regulatory Commission as an 'unusual event'.