Jefferson County sheriff’s investigators determined the Quarry fire near Deer Creek Canyon was started by humans, launching an arson investigation into a second Colorado wildfire this week. The causes of three Front Range fires remain under investigation with local sheriffs asking for public tips and receiving investigative help from state and federal agencies. Meanwhile, firefighters started gaining control of those fires on Friday while a fourth broke open in southwestern Colorado and charred more than 2,000 acres. Del Kleinschmidt, left, division chief for Jefferson County Sheriff’s Department, and Tammy Story, state representative for the area affected by the fire, talk as a helicopter prepares to refill with water as it fights the Quarry fire in Jefferson County on Friday, Aug.