DUGWAY — The U.S. Army's Dugway Proving Ground was on lock-down Wednesday evening as part of "an ongoing security operation," according to spokeswoman Paula Nicholson. The gates to the facility were closed and workers normally scheduled to be off at 5:30 p.m. were not allowed to leave, while those coming into the area were not let in. Dugway encompasses more than 800,000 acres of Utah's west desert, where more than 2,000 people call home. It is a government-owned facility used by U.S. Army Reserves and U.S. National Guard for maneuver training. It is also a U.S. Army Test and Evaluation Command center where tests are occasionally run on defenses against biological and chemical weaponry.