Two fugitive brothers suspected as potential domestic terrorists were found in southwestern New Mexico with stockpiles of drugs, weapons and about 200 pounds of explosives after 15 years on the run from authorities, a U.S. marshal said Saturday.

A tip earlier in the week led authorities to a rented home, where the brothers were arrested Friday on weapons, explosives and other charges from a 1991 warrant in Merriam, Kan., officials said.

Geoffrey Rose, 62, and Gregory Rose, 50, were thought to be aligned with white supremacist and anti-government groups, authorities said.

"We believe they were at risk of committing an act against the federal government," U.S. Marshal Gorden Eden said.

Military-style helmets, bullet-resistant vests and a marijuana-growing operation also were found on the property that was heavily guarded by motion detectors and dogs, officials said.

It was unclear how long the Roses had been in the state, Eden said.

"That's one piece of the puzzle many agencies are trying to figure out: Where have they been all these years and what have they been doing?" Eden said.