At 1958 hours, Companies 10 & 11 were dispatched to 3225 North 5th Street Hwy in Muhlenberg Twp for an odor of natural gas. Chief 10 arrived and already had a strong odor from the parking lot. Chief 10 took command adding to the assignment Co 13, 85 and EMS from 560. Crews on scene evacuated and performed a search from store to staore until confirming a broken pipe inside the Mattress Warehouse. Gas was shut down and the crews were able to safely ventilate the structure from the high LEL% readings that were present. Company 11 was clear @ 2113 hours.