We are not sure what component or system failed or malfunctioned. The truck is available at this time for inspection, there wasn't much left of the truck after it caught on fire. The passengers in the truck were in danger, because they didn't realize the smoke they were smelling was coming from the truck they were riding in. It was not until one of the passengers said his arm was hot, it was then they realized the truck was on fire. The fire seemed to have started under the seat. I am not sure what caused it. There were no warning lamps or messages prior to this incident. The vehicle has been inspected by the insurance company, in which the truck is a total loss. The sheriff office and Fire Department were on the scene.