Mudslide estimated to be 4 miles long, 2 miles wide, 250 feet deep.

Colorado authorities are searching for three people missing after a massive mudslide in Mesa County, the local sheriff's office said late Sunday. 

"This slide is unbelievably big," said Lt. Phil Stratton with the Mesa County Sheriff's Office. It's estimated to be about 4 miles long, 2 miles wide and about 250 feet deep.

The mudslide followed a day of rain and is located about 11 miles southeast of the town of Collbran, a community of about 700 people in western Colorado.

The missing are three men who live in the area and haven't reported back home after going to look at the slide, according to Heather Benjamin with the sheriff's office.

There are no reports of damage to structures in the remote area.

Roadblocks have been set up to keep people from the rural area.

Conditions are described as "very unstable" by authorities.