Transcript for Tribe on front lines against illegal Amazon loggers
the ABC news investigation, inside the Amazon rain forest. Amid a troubling new report. Deforestation has doubled from just a year ago. But tonight, a tribe is fighting back, capturing illegal loggers themselves. But as you're about to see tonight, when those loggers are then set free, some come back with deadly force. Here's ABC's Dan Harris and our team in the Amazon tonight. Reporter: Okay, so, they've got a prisoner. He's got his hand on his pistol, another on a machete. We're on the front lines of a secret war. We have no idea what we are getting into. An indigenous tribe in the Amazon, taking up arms, including rifles, knives, even bows and arrows, against illegal loggers destroying their land. We're right there as members a group that calls itself the "Guardians of the forest" raid a camp of outlaw loggers. "Oh my god," says one suspect, "He is going to kill me." All told, they capture seven loggers. There is abundant proof of the men's activities. Even notes on how many trees they cut down. This wood goes to local cattle ranchers, who build fences around their area and they're selling the stakes for those fences. And it even shows right here how much money they're making. The leader, whose name is laercio guajajara, lectures the suspects. Why did you agree to do this work? "Because," he says, "I don't have anything." Laercio says more than a third of his ancestral homeland has been destroyed. Scientists now worry that the Amazon may be at a tipping point. After raging fires and an increase in illegal logging, deforestation doubled in January compared to last year. After forcing the loggers to burn down their own camp, laercio's camp brings them to Brazil's federal police. Less than two months after we leave, laercio is ambushed and shot by loggers, his deputy killed. "This," he tells us, "Represents the beginning of the war." Just the beginning. Thanks to Dan Harris. And Dan will have much more of this secret war to save the Amazon later tonight on "Nightline" and then on hulu.
This transcript has been automatically generated and may not be 100% accurate.