By MyFM's Rick Michaels - The State Fire Marshal and the Northbridge Fire Chief say the cause of the vehicle fire at the Osterman’s Propane facility on Church Street in Northbridge two weeks ago was accidental. The fire originated in one propane delivery truck and spread to two others, causing an estimated $500,000 in damages. The investigation determined that the fire started in an area between the engine and the passenger compartment that contained a large quantity of electrical wiring. Due to the extent of damage to the wiring, investigators cannot say conclusively that it was an electrical fire, but there is no evidence of foul play. State Fire Marshal Peter Ostroskey and Northbridge Fire Chief David White, along with Northbridge Police and State Police assigned to the Office of the State Fire Marshal, jointly investigated the fire with the assistance from an automotive forensic technician.