The U.S. Forest Service said Friday that the Colorado wildfire that tore through 15 square miles and destroyed 48 buildings was human-caused. The Alexander Mountain Fire, started in late July, is now almost completely contained, but it joins a second that burned to its south that is also being investigated as arson. Three large fires burned in Colorado in the past two weeks, including the Alexander Mountain Fire, threatening urban centers north and south of Denver. Almost all have been contained. Investigators of the Alexander Mountain Fire did not say whether they believe the fire was started intentionally.