The report says that the mudslide is 2 miles wide and 4 miles long. "This slide is unbelievably big," the report quotes Lt. Phil Stratton with the Mesa County Sheriff's Office.
However, no damage has been reported so far. The area is very remote.
Heavy rains which lashed the region for most of the day contributed to the cause of the slide, says media reports. Officials have urged citizens not to go into the area.
Roads leading to the Highway 330 and Salt Creek Road, outside the town of Collbran, have been blocked for safety.