Fire investigators say a methamphetamine lab may have caused an explosive fire overnight. The fire was reported in the 3400 block of Fredericksburg Road just after 10 p.m. Monday. First responders were called to the Villa Motel because of smoke but then there was a small explosion in one of the rooms. Investigators believe someone trying to cook the methamphetamine caused it. No one was inside the room at the time of the explosion, officials said. No damage estimate is presently known. Arson has been called to investigate. Authorities are still looking for the person responsible.