A seemingly moderate wildfire on Fort Carson suddenly exploded to 2,800 acres within a few hours Sunday night, Army officials said. But the blaze was 80 percent contained by 8:30 p.m., they said, and firefighters planned to monitor the area through the night. Later, officials upped the containment level to 90 percent. The fire was reported about 1 p.m. at the Cheyenne Mountain Shooting Complex near Fort Carson’s Gate 20. At 4:30 p.m., the fire had scorched about 700 acres and forced an hours-long closure of southbound Interstate 25 between Mesa Ridge Parkway and Santa Fe Avenue exits.