Skippack crews were dispatched to Palmer Court for a Carbon Monoxide alarm on Friday afternoon. They arrived to find several adjacent townhouses with high levels of CO. As crews worked to find the source of the CO and ventilate the residences, Perkiomen Township Fire Co. was called to assist in ventilation. As both companies cleared the scene approximately 2 hours after arrival, we were both called to assist with a building fire in Upper Providence Township. Ladder 86 stood by at Collegeville Fire Company during this incident to cover any additional calls in the area. Skippack crews returned home about four hours after the initial call.