(Portland, OR)  --  Fire officials say a mill in North Plains was damaged by two fires Saturday morning.  The first fire destroyed a small building next to the large mill.  Later Saturday afternoon, a second fire started in a large hopper containing sawdust.  The fire spread to a trailer that was under the hopper.  Crews moved the trailer and doused the sawdust with water.  The first fire was caused by an electrical problem.  The cause of the hopper fire remains under investigation.  No one was hurt in the fires.