Three people are missing after a pair of mudslides in western Colorado on Sunday, which also affected a natural gas well pad, presumed to be operated by Occidental Petroleum Corp. (Oxy), and several other nonproducing gas wells.

According to reports, the slides occurred Sunday evening in Mesa County, on uninhabited land on Grand Mesa, the world’s largest flat-topped mountain. The first, smaller slide had cut off an irrigation system near West Salt Creek, and three men went to investigate. While they were in the area, a second, larger slide hit.

On Monday, the Mesa County undersheriff said the three missing men included Clancy Nichols, a 51-year-old employee of the county’s Road and Bridge Department, and his 24-year-old son, Danny. Also missing was 46-year-old Wes Hawkins.

Authorities said the slide measures 250 feet deep and is two miles wide and four miles long.

In a statement Monday, the West Slope Colorado Oil & Gas Association (WSCOGA) said as of Monday one well pad with three active gas wells near Collbran, CO, was affected by the slides. The association identified Oxy as one of its members affected by the slide.

“The wells were monitored remotely using telemetry and on Sunday showed no signs of spills or releases,” WSCOGA said. “Out of an abundance of caution, companies shut down the natural gas wells manually also conducting a physical assessment of the equipment. Connective pipelines associated with the natural gas wells were depressurized and drained.

“In addition a limited number of nonproducing natural gas wells may have also been affected which pose no immediate risk factors to the public or environment.”

WSCOGA Executive Director David Ludlam said preliminary results showed the slides had caused minimal damage to oil and gas production equipment in the vicinity.

“Investments in training and technology allowed our member companies to remotely monitor and manually shut down the small number of wells at risk. We believe all potentially affected natural gas locations are secure,” Ludlam said. He added that operators “with wells in the area secured our efforts will shift to assisting the citizens of Plateau Valley. Our member companies are meeting today discussing how best to provide resources to local officials and assist in the search and rescue and cleanup efforts.”

Ludlam said other companies in the Plateau Valley region, but not with assets in the slide area, include Axia Energy LLC, Piceance Energy LLC and Encana Corp.