GREELEY, Colo. — An investigation is underway after workers at an oil and gas site in northern Colorado found what appear to be human remains.

The Greeley Tribune reports the workers were constructing a new pipeline at the site in rural Weld County when they discovered the bones Tuesday night. Sheriff Steve Reams says his deputies are treating the recovery of the remains as a homicide investigation until evidence proves otherwise.

Prosecutors with the district attorney’s office were at the site Wednesday morning.

Reams says the bones do not appear to be part of an old burial ground. No other information was released.