An O-DOT incident response truck was destroyed by fire Wednesday morning.  It was stopped on the side of I-205 southbound near Gladstone assisting with a small crash when the fire erupted.  O-DOT's Don Hamilton says the driver was out of the truck when it happened.  Fire crews closed the freeway until the fire was out.  The trucks carry flares and extra fuel to assist drivers, and that made the fire more dangerous than normal to fight.  O-DOT has eight trucks in the Portland area.  The cause of the fire is under investigation.