First, the cops fire tear gas, then rubber bullets. As protesters flee, they move on to live rounds.
One man, wearing only a pair of shorts, stops to raise his hands in surrender. He is knocked to the ground and given an extended beating by eight energetic policemen in black body armour and helmets.
Demonstrators who meet the rifle butts and truncheons of Peru's security forces are the lucky ones, though.
Dozens more are shot as they fled. You can see photographs of their bullet-ridden bodies, charred black by a fire that swept through the scene of an incident dubbed "The Amazon's Tiananmen".
The events of Friday, 5 June, when armed police were sent to clear 2,000 Aguaruna and Wampi Indians from a road-block at Devil's Bend, a stretch of highway near the secluded town of Bagua Grande, have sparked international condemnation and thrown Peru's government into crisis.
Until now, they have remained shrouded in mystery. These pictures, taken by two Belgian aid workers, Marijke Deleu and Thomas Quiryneen, are the first to emerge from the scene, and provide compelling details of a chaotic confrontation that led to the reported killing of at least 60 people, with vast numbers still unaccounted for.
"At first, we saw police firing guns and tear gas at a mass of protesters," said Deleu, who reached the highway at 6am, roughly an hour after heavily armed police had begun evicting the protesters.
"Then we saw them beat people and kick people who they were detaining on the ground. Later, I saw them shooting people in the back as they started fleeing."
A dossier of the photographs, many of which are too graphic to be printed, will be shown to MPs at the House of Commons on Monday by Deleu and Quiryneen, who are volunteers for Catapa, a Flemish organisation supporting indigenous communities in Peru, Bolivia and Guatemala.
Called "Death at Devil's Bend," it attempts to explain what happened when police tried to evict the indigenous tribespeople, who had been blockading the road for several weeks in protest at new government laws to allow energy and mining companies to exploit vast swathes of their ancestral homelands.
One series of photographs shows police stopping a passing ambulance. They force four injured protesters out of the vehicle, and beat them in the roadway for several minutes, claiming they have been carrying concealed weapons.
Another series, taken later in the day shows rows of wounded being treated in local hospitals. Nineteen are counted in Bagua Grande hospital; 47 in Bagua Chica hospital. Many have heavy bruising, and bandages covering bullet wounds. Bodies are photographed being loaded into mysterious vehicles, bound for an undisclosed location.
Further pictures, which will only fuel rumours that the Peruvian government orchestrated a cover-up, show twisted corpses of native Indians lying by the side of the road, roughly 870 miles north of Lima.
When tribal leaders tried to collect the bodies they came under fire and were refused access. By the next day, the corpses had disappeared.
The Peruvian President, Alan Garcia, has claimed 32 people were killed in the incident, of which 23 were police officers. However human-rights lawyers and news reports put the number of confirmed deaths at closer to 60, and say hundreds of missing people have yet to be accounted for.
Until this week, many international observers have been unable to visit the Devil's Bend, where a curfew was imposed in the wake of the incident. As a result, pressure groups have accused Garcia's security forces of burying and burning corpses to hide the extent of the death toll.
"There needs to be an independent investigation into to establish exactly what happened," said Jonathan Mazower of Survival International, which will today publish Deleu and Quiryneen's dossier on its internet site.
"Our initial reaction to these photographs is that they are dramatic, and may provide the first impartial account of what actually went on here."
The pictures emerged as Alberto Pizango, the head of Aidesep, the organisation representing 56 of Peru's indigenous tribes, arrived in Nicaragua, after being granted political asylum.
Last week, he was charged with "sedition, conspiracy and rebellion".
Meanwhile President Garcia has been forced to suspend the introduction of laws allowing foreign companies to exploit the rainforest.
His Prime Minister Yehude Simon resigned on Monday, joining populist minister Carmen Vildoso, who quit last week during a general strike in protest at the incident.