VIDEO: Crews battled a large mobile home fire in the Prairie Ridge neighborhood of Bonney Lake on Friday morning. East Pierce Fire and Rescue crews responded to a residential structure fire in the 22400 block of 127th Street E to find a well-involved mobile home fire. A defensive attack was begun, but the fire spread to two vehicles and a camper, and EPFR say there was an explosion that may have been a propane tank. The cause of the fire is under investigation, but a Pierce County Sheriff's Department spokesperson told KING 5 it is believed to be arson. People are asked to avoid the area.