Crews from FS03, FS02 and FS04 were alerted to a vehicle fire threatening a structure in the 8700 block of Gas House Pike late afternoon. Engine 31 arrived and had a work truck with fire from the rear/storage area. Paramedic Engine 23 taking position on a hydrant supplied water to Engine 31. Crews utilized two inch and three quarter hand lines to extinguish the fire which contained mixed fuels. The work truck was a welders truck and being used as such when a section of electrical wire apparently grounded out on the truck creating a spark to start the fire. Units continued to flow water to cool and extinguish the fire.