Federal geologists are on the way to assist in the search for three missing people after a Colorado mudslide left the community "praying for a miracle right now," Mesa County Sheriff Stan Hilkey said today.

"We're praying," he said at a news conference.

"We hope that they might been stranded. We have flown the area and have not seen anything from the air."

He said the missing people, whom he did not name, went to check Sunday on the irrigation system, which generates water for ranches in the area. "It's tied to the rain," he said. "There's no doubt that the slide is tied to the runoff and the amount of rain."

Hilkey said no homes in the rural area near Collbran, Colorado, have been affected, and there have been no evacuations. "The slide came down with so much force and velocity that it came down a hill and then back up a hill, so the power is remarkable," he said.

Local authorities have also called for additional resources that include scientists from the U.S. Geological Survey.

The first reports of the mudslide were called into the Plateau Valley Fire Department Sunday night, along with reports that three Mesa County residents were missing.

The Fire Department responded as soon as a witness called about "a noise that sounded like a freight train that is attributed to the slide," Mesa County Sheriff officials said earlier today.

The mudslide is estimated to be about 4 miles long, 2 miles wide, and about 250 feet deep in many places, according to an official statement issued by the Sheriff's Office.

"This slide is unbelievably big," Lt. Phil Stratton told ABC News.

Rain had fallen in Mesa County most of Sunday and officials there said that it most likely contributed to the cause of the slide. "We anticipate more rain in the forecast today," Mesa County Sheriff's Office spokeswoman Lisa McCammon said earlier today.

The mudslide area is remote and no structures have been reported damaged, she added.

ABC News' Bonnie Mclean contributed to this story.

(Photo Credit: ABC News)