Fred Jobe, sheriff of Custer County, told the Rocky Mountain News the group appears to be the Fundamentalist Church of the Latter-Day Saints.

Warren Jeffs, the group's leader, was convicted in Utah of forcing a teenage girl into marriage with her 19-year-old cousin. In Texas, authorities recently raided an FLDS compound and seized hundreds of children.

Jobe said the group does not appear to be breaking any laws in Colorado.

"They seem to be always adding on, building, doing something around the places," said Jobe. "That seems to be an ongoing thing."

While polygamous marriages are not legally binding, plural relationships among consenting adults are not illegal. In Texas, authorities found evidence of teenage girls who were married to older men and became pregnant long before they reached legal age.