LA MORA, Mexico - For decades, this small village of American Mormons in the mountains of northwestern Mexico coexisted peacefully with the region's most powerful drug cartel.

The Americans rolled down their windows at the cartel's checkpoints. They nodded to the sicarios at local horse races and shared pomegranates during the harvest. When the cartel vehicles needed repair, La Mora's American mechanic fixed them for the same fee he charged his neighbors.

Until this week, living as an American in one of Mexico's most dangerous valleys meant maintaining an uneasy truce with the traffickers: "Basically, it was 'We won't bother you if you don't bother us,' " said Adam Langford, whose great-grandfather was one of the first American Mormons to move to Mexico in 1880.

Then, on Monday, Nov. 4, it became clear that no agreement could insulate La Mora from Mexico's rising violence. That morning, gunmen stopped three vehicles on a dirt road outside of town, killing three women and six children, shooting babies at close range and targeting a mother as she begged for her children's lives.

The Mexican government has suggested that the vehicles were attacked by mistake. But here in La Mora, that explanation makes little sense.

Instead, residents here believe the families were targeted intentionally by a cartel from the neighboring state of Chihuahua - maybe as revenge for the community's proximity to the local cartel in Sonora, where La Mora is located. The massacre comes amid an intensifying turf war between the cartels that residents had watched nervously for over a year.

"We watched as things got more tense, but we thought the same thing we always did - they won't come after Americans," said Amber Langford, 43, a midwife in La Mora. "They would stop as at a checkpoint and ask what we had. We'd say 'honey' or 'potatoes,' and they'd let us go."

La Mora was established in the 1950s, an offshoot of the fundamentalist Mormon movement. For decades, it remained largely cut off from the United States and the rest of Mexico, without electricity or running water. Children welded their own bicycles with metal rods. But the community began to thrive in the 1990s and early 2000s as residents developed pecan farms and ranches and brought money back from seasonal work across the border.

They built homes designed for an American suburb. When friends in the United States asked about their safety, many explained that they rarely locked their doors. They allowed their children to roam free in the foothills of the Sierra Madre. They had two schoolhouses - one for Spanish and one for English - and the students, fluent in both languages, divided their time evenly.

But amid the idyll, the residents of La Mora recognized their community's strategic importance. It was directly off an unpatrolled dirt road that led to the United States border, a gem in the crown of any trafficker.

In 2009, two men related to the La Mora families but living in Chihuahua were kidnapped and killed, allegedly by the state's biggest drug cartel. It was a shock, suggesting that maybe the community's dual citizenship wasn't enough to insulate the American Mormons of northern Mexico from rising violence.

But many residents of La Mora believed that their unlikely relationship with the cartel in their state would protect them. Although there was little police presence in the area, some believed the cartel - sometimes known as the Sonora cartel - had come to serve as a kind of shadow police force.

"The fact is that the state didn't provide law and order, but the cartel did," said Adam Langford, who served twice as mayor of the municipality.

Sometimes, the men at the checkpoints would apologize after stopping them.

"They would say, 'Sorry guys, we are just guarding our territory,' " said Kenneth Miller, 32.

In recent months, there were signs that the peace was deteriorating. For the first time, the local cartel mandated that the families of La Mora not buy their fuel from Chihuahua, which would fund the rival cartel. Unfamiliar men manned the usual checkpoints. They appeared jumpier, sometimes pointing guns at passersby. Rumors spread about the intensifying turf war between criminal groups.

"People started asking each other, 'Is it time to move back to the U.S.?' " said Amber Langford. The population dwindled to about 100.

Across much of Mexico, the strength of the cartels - and the inability of the government to control their influence - has been on daily display.

The number of homicides climbed to 33,341 last year. Another 40,000 people are missing.

The cartel attacks have become particularly brazen. In August, 27 people were killed in a Veracruz bar when the doors were locked and the bar was set alight. Last month, 14 police officers were killed in an ambush in Michoacan. Also last month, in the city of Culiacán, the Sinaloa cartel overpowered government security forces and forced the release of Ovidio Guzmán López, one of the country's best-known drug traffickers.

Residents of La Mora began taking precautions. They traveled in convoys when moving between Sonora and Chihuahua. They decided it was time to secure legal firearms.

On Monday, when the three women and their children left town, Rhonita Miller paused before leaving and said to her mother-in-law Loretta Miller: "I have a bad feeling about this. Maybe I shouldn't go," Loretta recalled.

Less than an hour later, Rhonita Miller was killed with her four children. When residents found her car, it was on fire, apparently set alight by gunmen.

The other victims were found later. Two surviving children walked for hours through the wilderness after escaping. One of them recounted that gunmen had fired at him as he ran into the brush.

Within hours, the massacre sent a shock wave through Mexico and the United States, renewing questions about Mexico's failure to secure its territory, prompting President Trump to offer up the firepower of the U.S. military.

The residents of La Mora began preparing for the funerals. They made wooden coffins. Amber Langford, the midwife who had delivered the children who were murdered, embalmed their bodies. As they mourned, they became aware of how their community's ordeal had reinvigorated a debate about how to end Mexico's years of bloodshed.

"I'm not saying I want the U.S. to come down here to revenge my family," said Kenneth Miller, whose sister-in-law was killed. "But to help all of Mexico."

For now, their quiet town has been flooded with Mexican security personnel, who will inevitably leave in the coming weeks. Everyone here seems to agree: Any reprieve from violence, in the civil war between cartels, is only temporary.

"The question we all have here," said Adam Langford, "is how does this thing end?"

This article was written by ____, a reporter for The Washington Post.