A wildfire on the edge of metro Denver has crept within a quarter-mile of evacuated homes. Planes and helicopters were dropping water on the fire west of Littleton on Thursday. Smoke plumed over ridges, and nearby residents watched from a distance. Officials say they’re hopeful to save hundreds of threatened residences. Firefighters have faced sweltering temperatures that have sidelined some with heat exhaustion. The fire was among several threatening heavily populated areas of the Colorado foothills, including one in which a person was killed. Almost 100 large fires are burning across the western U.S. The largest is in Northern California. It has destroyed more than 400 houses and other structures.