PHOTOS: Firefighters are working to contain Utah's largest active wildfire. The Neck Fire has burned 19,017 acres and is 30% contained, according to Utah Fire Info. The blaze sparked just north of Cedar City on Sept. 5. Officials believe lightning caused the fire to start. A total of 339 personnel are at the front lines working to contain the flames. Officials are asking drivers on Highway 130 to slow down in the area near the fire. The only closures that have been issued are for unpaved roads in the vicinity of the flames. A Red Flag Warning is in effect until Wednesday. Utah Fire Info reports a strong cold front with strong winds will come move in throughout the next few days.