PORTLAND, Ore. - So far, 25 people have been arrested in connection with the standoff between a militia and federal officials on a federal wildlife preserve in Oregon.

As the FBI sweeps in to collect evidence from the scene of the occupation, officials are discovering the dirtier aspects of living in a remote wildlife refuge that may come back to haunt the occupiers.

The group that moved in to the Malheur Wildlife Refuge near the town of Bend set up a large outdoor camping site that, according to Reuters, was near artifacts and sacred burial grounds of the Burns Paiute Tribe.

Get Breaking News Delivered to Your Inbox

CBS affiliate KOIN in Portland reports the campsite had "large food stores that are spoiling" and "significant amounts of human feces in and around an outdoor camping area."

Additionally, FBI agents found large amounts of firearms and explosives, and are concerned some of the abandoned cars may by booby-trapped.

Federal prosecutors said Wednesday nine additional people from six states have been charged in connection with the armed occupation of the wildlife refuge.

The U.S. Attorney's Office in Oregon says seven of them were arrested Thursday and two remain at large.

That means a total of 25 people have been charged with the standoff. They all face the same felony count of conspiracy to interfere with federal workers.

The takeover began Jan. 2 after two Oregon ranchers were returned to prison over fires they set which spread to federal property nearby. Most of those in the militia appear to have come from outside the region, and are part of a growing militia movement in the West.

The brothers Ammon and Ryan Bundy led the takeover. Their father Cliven Bundy was famous for a standoff at his ranch in Nevada, the eventually led to his arrest last week in Portland.