Fire department crews are trying to get a wildfire, north of Denver, CO, under control.  The fire, which broke out monday, has now spread across almost 1000 acres.  Helicopters and air tankers are fighting the fire from above, while crews are battling the flames at ground level.  The fire is burning near several homes, but local fire officials say that none of the buildings are threatened at this time.  It is still unknown who is responsible for the fire.