OCOTITO, Mexico — On an early spring morning, in the desert of Mexico’s southwestern Guerrero state, a half-dozen rusty pickups speed toward a line of late-model 4x4s blocking the road.

As armed men leap from the truck beds, the drivers swing across the tarmac, forming an opposing blockade of ancient Nissans and Ford Rangers.

Crouched behind their respective barricades, their elbows propped on hoods and fenders to steady their aim, some 40 men now draw down on each other with every kind of firearm imaginable: bolt-action hunting rifles, automatic shotguns, old-fashioned six-shooters, Uzis and M16s, even a few AK47s.

It’s just a few hours after dawn in these jagged foothills; the temperature is already in the mid-80s and climbing fast—but the tempers of the men facing off behind their vehicles are rising even faster.

“Cobardes! Traidores!” shout those enfiladed behind the big-wheeled, showroom-new 4x4s. Cowards! Traitors!

“Cartel assassins!” comes the response in Spanish from the line of old trucks on this forlorn stretch of Interstate 95 – the so-called Heroin Highway, considered so dangerous that the U.S. State Department lists it as off-limits to American citizens.

At least half of all the heroin produced in Mexico comes from Guerrero, much of it traveling southwest along I-95 to the Pacific port of Acapulco, where it’s packaged and shipped north. Mexican state and federal police have so far proven themselves unwilling or unable to challenge cartel supremacy in Guerrero – forcing a growing number of the state’s citizens to fend for themselves.

The deadlocked gunmen on the highway this morning are citizens from rival factions. They’re “community police” – those on one side allied with law enforcement and those on the other said to back local drug traffickers. This is what vigilante justice often looks like in rural Mexico, where state authorities provide little more than a fever dream of security.

Up until a few months ago, the United Front for the Security and Development of Guerrero (FUSDEG) and the Union of Organized Peoples and Organizations of Guerrero (UPOEG) were on the same team. But they parted ways last December, over UPOEG leadership’s use of torture and charges of affiliation with organized crime. Now the former allies are at war.

The night before the highway showdown, there was a palaver over militia jurisdiction in the nearby town of San Juan del Reparo, after which UPOEG allegedly opened fire on a FUSDEG column as it was leaving the village. In the ensuing battle, UPOEG lost two men and FUSDEG lost six, with four more wounded. Of the FUSDEG fallen, one was beheaded and another had his face peeled off—an increasingly common cartel tactic. Scores of prisoners were taken by both sides.

A few hours later, out on the highway, the standoff is about to boil over. As the taunts crescendo and gunfire seems imminent, a wide-shouldered campesino in battered spectacles—his flak jacket reinforced with salvaged sheet metal—steps out with a walkie-talkie from behind the barricade of older trucks. Salvador Alanis, age 37, is the top-ranking security chief for FUSDEG.

“Please hold your fire,” Alanis calls out. “We’ve come in peace for the prisoners,” This reporter, in a show of gringo bravado, has followed Alanis out into no-man’s land—holding up a press pass like a talisman in one hand, camera atremble in the other.

Alanis now shouts: “We don’t want any more killing,” although it’s unclear if he’s talking to his own troops, or to me, to the UPOEG lines, or himself.

Scenes like these are all too common in Mexico. Volunteer police groups like FUSDEG and UPOEG are protected under Mexican law and are active participants in Mexico’s U.S.-backed drug war. Community police units, usually made up of indigenous farmers, operate in eleven Mexican states. Guerrero alone is home to seven individual militias. The volunteers’ basic expenses are partly funded by their respective municipalities, but in some cases kidnapping, extortion, and drug trafficking help to make ends meet.

FUSDEG has chosen to align itself with federal law enforcement, even joining state-funded officers on patrols. On a single day in February, FUSDEG detained 18 people for narcotics trafficking in the town of Petaquillas, and seized 40 kilos of marijuana. UPOEG, on the other hand, is led and financially supported by a wealthy businessman named Bruno Placido—a state congressional candidate with alleged ties to the underworld.

The ideological schism causes predictable – and often bloody – clashes between these proxy militias.

At the standoff on the highway outside Ocotito, FUSDEG’s security coordinator Alanis is led at gunpoint through the enemy roadblock, then hustled into a clapboard house on the other side, to discuss terms for the prisoners taken by UPOEG the night before. Sitting at a table piled high with seized rifles, yet managing to look defiantly bored, Alanis stares down the rival leadership.

“You had no right to fire upon us in our own territory,” he tells the UPOEG council. “San Juan del Reparo has voted—and you must respect the assembly. It’s FUSDEG territory now.”

“You shouldn’t have shown up [to the meeting at San Juan] with the federal police,” counters UPOEG commissioner Gaudencio Abraján. “You know we don’t like the government in our business.”

“Por favor – that’s no reason to start shooting people,” says the FUSDEG chief. Abraján just shrugs from across the rifle-laden table.

Meanwhile, outside in the blinding, high-desert sunshine, another UPOEG officer lectures some of the men who pulled off the ambush the night before.

“I don’t want to hear about this kind of thing happening again,” the officer barks at the volunteers, who hang their heads and smile slyly. Their weapons, like their trucks, are noticeably better than FUSDEG’s, and some of them sport designer apparel.

“If they’re in our territory—we can’t retaliate?” says one man in a black t-shirt with silver letters across the chest that read, in English, “I’ve just got to be me.”

“No, no, no,” chides the UPOEG commander. “No shooting anybody—unless it’s absolutely necessary,” and the killers, still grinning, hang their heads again.

Later that same night, after local human rights workers have arranged a prisoner exchange, the FUSDEG captives are finally united with their families in the state capital of Chilpancingo. Some of those seized the night before are still suffering from untreated gunshot wounds. Others are so traumatized by torture that they weep openly.

“They disarmed me, they took my shoes. Then they kicked me and beat me with their rifle butts,” says a man who calls himself Angel. His face weathered from years of hardship and manual labor under the sun, he declines to give his last name for fear of reprisal. “But I was lucky,” Angel says. “[UPOEG members] stabbed two other [FUSDEG members] to death while I watched. They killed them in the road like it was nothing.”

Federal police in body armor mingle with the human rights team in the street while freed hostages hug worried relatives. But the officers don’t provide any assistance to the wounded, and no statements will be taken from the witnesses tonight or in the days to come. Nor will arrests be made in connection with the killings during the ambush, nor in the cases of the beheaded and de-faced victims. UPOEG boss Bruno Placido is still running for office, and the attorney general has yet to question him in connection with the killings, despite concerns voiced in the local press.

“The drug lords still run the show around here,” sighs FUSDEG’s Alanis, during the prisoner exchange. The security officer hasn’t slept since the night before the unprovoked attack that claimed half-a-dozen of his men, and his eyes are puffed and raw-red behind his bent, poor-man’s glasses. “The authorities won’t do anything to help us. We’ve known that for a long time.”

“Los únicos que pueden salvar a nuestras comunidades de los carteles – somos nosotros mismos,”Alanis says. The only ones who can save our communities from the cartels – are us.