This 2010 image shows part of an uncontacted Indian tribe in western Brazil. The tribe has disappeared since a group of armed men (presumed to be Peruvian drug traffickers) overran a Brazilian guardpost near the tribe's lands. Brazilian officials are now looking for signs of the missing tribe.

Editor's Note: Due to a typo, the original version of this article stated that the guard post is 32 miles from the Peruvian border. In fact, the post is 12 miles from the border. We apologize for the error.

An uncontacted Amazon tribe that made headlines earlier this year after being filmed from the air is feared missing after presumed drug traffickers overran the Brazilian guards posted to protect the tribe's lands.

According to tribal advocacy group Survival International, Brazilian officials can find no trace of the Indians in the area after heavily armed men ransacked the guard post in western Brazil about 12 miles (20 kilometers) from the Peruvian border. Like other uncontacted tribes, the Indians live a traditional life in the forest and do not have contact with the outside world.

Workers from FUNAI, the government bureau of Indian affairs, found a broken arrow in one of the men's backpacks, raising fears for the tribe's safety.

"We think the Peruvians made the Indians flee," Carlos Travassos, the head of the government's isolated Indians department, said in a statement. "Now we have good proof. We are more worried than ever."

[Top Urban Legends Debunked]

Lost tribe

As many as 2,000 uncontacted Indians may live in the Javari Valley of the western Amazon, Survival International estimates. Brazilian officials keep an eye on tribal lands but do not force contact with the inhabitants. In February, Brazil's Indian Affairs Department released aerial photos and film of the tribe that is now missing, revealing thatched dwellings, tribe members in red body paint, and gardens full of manioc tubers and papaya. [See the aerial photos ]

Now the Indians seem to have disappeared. According to Survival International, police found a package containing 44 pounds (20 kilograms) of cocaine in the area. That could mean that the Envira River, where the Brazilian guard post is located, is now an entry point into Brazil for Peruvian cocaine smugglers, they said.

According to local reports, police have detained one man, a Portuguese national who was arrested and deported for drug trafficking in March. Jose Carlos Meirelles, who headed the remote guard post, is now back in the area and reported that several groups of men armed with sub-machine guns and rifles are in the forest near the base.

Guns aren't the only threat to uncontacted Indians. Common diseases can also kill them, because they have not built up immunity to the viruses and bacteria outside their forest home. According to Survival International's uncontactedtribes.org, there are about 100 uncontacted tribes in existence worldwide.

"This situation could be one of the biggest blows we have ever seen in the protection of uncontacted Indians in recent decades," Travassos said, referring to the possible drug traffickers. "It's a catastrophe."

You can follow LiveScience senior writer Stephanie Pappas on Twitter @sipappas. Follow LiveScience for the latest in science news and discoveries on Twitter @livescience and on Facebook.