A helicopter lands and police from Brazil's IBAMA environmental protection agency jump to the ground, weapons drawn.
Within 15 minutes they round up six miners and seize rifles, machetes and chain saws inside the camp in the middle of protected land in Brazil's northern Para state.
"This is a .38. Out here it's used in armed confrontation," says Jaime Pereira Costa, a hardened veteran who has been with IBAMA's special forces for 35 years. "That's what they used to shoot at our helicopter earlier this year."
IBAMA says the small illegal gold mines carved into hidden corners of the Amazon are a big business, tearing down trees and contaminating rivers with mercury.
According to the British journal Environmental Research Letters
, a global gold rush has led to a significant increase in deforestation throughout South America, destroying 1,680 square kilometers (about 649 square miles) of tropical forest between 2001 and 2013.
Using satellite imagery, IBAMA has swooped down on the mine a couple of months after excavation started. Six miners sit barefoot on logs while agents confiscate small nuggets of gold and ledgers full of annotations.
The man in charge of the mine, Jose Nilton Azevedo, offers to show the precarious tent he shares with the workers.
"I know we're destroying the trees," he said. "But unfortunately it's the only way for those of us who live here and don't have jobs or studies."
Pointing to pots of rice on a makeshift stove and hammocks strung from posts, he asked, "Do you think we would live like this if we didn't have to?"
And yet the Lonking excavator dredging holes for his mine is worth more than $100,000.
"We're fighting a war, a war to protect the environment in Brazil," IBAMA agent Otavio Cesar Ramos said. "They have radios and weapons and expensive equipment, and they know what they're doing."
IBAMA, on the other hand, has under 2,000 agents tasked with monitoring the entire Brazilian Amazon, estimated at about 3.3 million square kilometers (1.3 million square miles). Brazil is home to 60% of the Amazon rain forest.
On this raid, they arrest the leader of the mine and set the other workers free. The workers climb into a motorized canoe and head downriver.
But they destroy the camp, burning the excavator, generators and pumps as well as the tent.
"We need to make sure nobody is tempted to come back and start it up again," Ramos said.
No more than 2 degrees
Burning rain forests and deforestation account for anywhere from 5% to 20% of global greenhouse gas emissions per year, according to calculations made by climate scientists. And the Amazon basin -- which is more than twice the size of India at 6.7 million square kilometers (2.6 million square miles) -- contains by far the largest remaining rain forest in the world.
Conserving the Amazon, therefore, must be a central part of efforts to limit global warming going into the U.N. climate summit in Paris in December
With some 80 world leaders on hand, the aim is to come up with a single agreement on tackling climate change, with the goal of capping warming at 2 degrees Celsius
(3.6 Fahrenheit) over pre-Industrial Revolution levels.
There has been much good news out of Brazil. Here, deforestation has declined significantly since 2004, thanks to the creation of national parks and enforcement of laws.
By 2012, Brazil lost 460,000 hectares (1.14 million acres) of forest, while Indonesia lost about 840,000 hectares (2.08 million acres) despite its forest being roughly a quarter of the size of the Amazon, according to the journal Nature Climate Change.
Brazilian President Dilma Rousseff
has pledged to achieve zero illegal deforestation in the Amazon by 2030.
The problem is illegal activity has not been brought under control, and the Brazilian government has extended amnesties to ranchers and farmers in recent years, which critics say have prompted a spike in deforestation in 2014 and 2015.
According to satellite imagery analyzed by the watchdog group IMAZON
, Amazon deforestation in 2014 and into the beginning of 2015 had more than doubled compared with the same time period a year earlier.
The 'Blonde Devil'
IBAMA has set up its regional headquarters in Novo Progresso, or New Progress -- a city founded less than 24 years ago as loggers, ranchers and large-scale farmers pushed into the Amazon rain forest.
The main avenue is lined with gold pawn shops and sawmills. The vehicle of choice: big-wheeled pickups.
Here, IBAMA agents' every moves are monitored. The national coordinator, 32-year-old Maria Luiza Goncalves de Souza, has been dubbed the "Blonde Devil" by her enemies.
"As soon as I arrive, the radios start buzzing -- they report where I'm staying, where I eat, and where our trucks are headed," she told CNN as her troops convene for a strategy meeting.
After six months of studying satellite images that show clearings in indigenous territory, IBAMA is planning a night sting on illegal loggers.
"We can't afford for this to be leaked," Souza said as her agents get the details for the first time. "They've got more money and better technology so we have to be careful."
At dusk, we hit the road in unmarked pickups for a five-hour drive along potted roads. At the same time, a convoy of IBAMA vehicles takes off in the opposite direction in the hopes of confusing the loggers.
We finally pull up near land that belongs to a Kayapo indigenous tribe.
"They're hauling out 19 trucks a day from indigenous territory," Souza said. "They're stealing from the country, and it's our job to stop them."
The first truck takes them by surprise, and state agents fire rounds into the engine to force it to stop.
They arrest the driver and monitor the radio. A dispatcher warns that something seems to be afoot and orders the trucks to "run over anything that gets in your way."
But four more trucks carrying massive logs are halted at the barricades without any armed confrontation.
Only at the very end are conventional police called in to take the drivers into custody. IBAMA hopes to use the drivers to build a case against the major players in the illegal logging industry.
And then the eco-police use one of the few deterrents they have at their disposal: They torch the illegal logs and all five trucks carrying them, a cache worth nearly 1 million reais or about $250,000.
"We hit them in their pocketbooks. That should keep them busy for a while," Souza said as huge flames leap off the trucks into the night sky.