PHILADELPHIA (AP) — A mother and teenage daughter have died of injuries they suffered in a fiery explosion inside their food truck earlier this month, authorities said Thursday. Eleven other people were injured, three critically, in the explosion, which investigators believe was caused by a propane tank leak ignited by cooking grills. Nearby surveillance video captured the explosion, which was followed by a huge fireball that engulfed the 25-foot truck and set a utility pole on fire.