A Mexican cartel and a polygamous cult have been feuding for years. Now nine people are dead.

On Monday, a convoy carrying nine members of a Mormon family were massacred in Mexico.

Three mothers and their six children including six-month-old twins were found alight in a bullet-ridden vehicle in the country’s north.

A total of three cars were fired at by gunmen in the middle of the day, with eight children surviving the attack. One, a 13-year-old, hiked for six hours back to his family to tell them what happened.

Today did a story about the history of the family. Post continues after video.

Devin Blake Langford watched his mother and two brothers die before hiding his other siblings in the bushes – covering them with branches to keep them safe before he left for help, reported CNN. When he didn’t return as it started to get dark his sister, nine-year-old McKenzie, who’d been shot in the wrist, set out to look for him. She walked for four hours before being found by rescuers.

Meanwhile, the other children hid for 10 hours in the barren landscape. Five are in hospital with injuries, but their conditions are stable.

The slaughter shocked the world, with 200 shell casings found at the scene. Why would a family be brutalised in this way?

The victims who were all dual US-Mexican citizens were: Rhonita Maria Miller, 31, and four of her children including 12-year-old Howard Jacob Miller, Krystal Bellaine Miller, 10; and twins Titus Alvin Miller and Tiana Gricel Miller. Christina Marie Langford Johnson, 31, and Dawna Ray Langford, 43, and her two children, 11-year-old Trevor Harvey Langford and two-year-old Rogan Jay Langford.

They were all part of a local community who are a breakaway branch of the Mormon religion, and have a history of speaking out against Mexican drug cartel violence. While the victims had different last names, they all have ties to the LeBarón name.

The cult behind the LeBarón name.

After The Church of Jesus Christ of Latter-Day Saints abandoned the practice of polygamy in 1890, many Mormons moved south from America to Mexico to continue the practice. Alma Dayer LeBarón moved his two wives and eight kids south in 1924 and started a farm called "Colonia LeBarón" in Chihuahua which eventually included more than 30 families.

When Alma died in 1951, he passed the leadership of the farm to his son Joel. But his other son Evril formed his own sub-church that took on a cult following. He eventually had his brother Joel killed. Anna LeBarón who was one of his 51 children escaped her father's cult when she was 13 and went on to write about her experience in her 2017 memoir, The Polygamist's Daughter.

My memoir is called The Polygamist’s Daughter.

I share my story of being born & raised in a violent, polygamist cult that was led by my father, Ervil LeBaron.

I share my journey to healing & give hope to readers that have experienced trauma & abuse. https://t.co/CShfwgHTJJ

— Anna LeBaron (@annaklebaron) June 28, 2018

Media outlets at the time dubbed Ervil the "Mormon Manson" because of his organised mob-style hits on those who stopped believing in him or who were "rivals" of his. Anna also spoke in her book of her father's community enduring beatings, underage marriage and other abuse.

The cult was disbanded in the early 90s and Ervil died in prison in 1981.

In 2009, the LeBarón family made headlines after a drug cartel kidnapped a 16-year-old member of their community, holding him for $1 million in ransom money which they refused to pay.

Eventually the government intervened and the boy was returned. After that incident the LeBaróns armed themselves, which is a violation of Mexican law.

Later the same year in retaliation for the failed kidnap, a cartel reportedly kidnapped Benjamin Le Baron in the middle of the night. He was beaten and murdered alongside his brother-in-law who tried to save him.

Another brother, Julian LeBarón, joined a high profile peace movement after the murders, which was founded by poet Javier Sicilia. As the peace activist side of the family grew, the LeBaróns became more and more integrated into Mexican society with one family member even marrying a Mexican woman in a Catholic ceremony.

They, like their neighbours, have long been vulnerable to the violence of northern Mexico where they live.

"Caught in the crossfire" or premeditated?

It was originally reported the family was killed because they were mistaken for a rival cartel gang, especially as the region they were murdered in has long been fought over by the Sinaloa cartel and La Linea gangs. The Mexican Security Minister Alfonso Durazo and US President Donald Trump both suggested they were just "caught in the crossfire".

A wonderful family and friends from Utah got caught between two vicious drug cartels, who were shooting at each other, with the result being many great American people killed, including young children, and some missing. If Mexico needs or requests help in cleaning out these.....

— Donald J. Trump (@realDonaldTrump) November 5, 2019

But relatives of the family think the murderers knew exactly what they doing - targeting the LeBaróns for speaking out against their violent ways. They'd recently been threatened by cartels about "where they could travel" and believe the attack was meant to stoke fear within their community.

Mexico's Foreign Minister, Jorge Castañeda, agrees, telling CNN, "They had stood up to the drug cartels and they did have certain frictions either with the cartels of with neighbouring communities over water rights".

On Tuesday, Mexican authorities announced an arrest, but by Wednesday he was let go after investigators learned he wasn't involved. Another man has since been arrested after being found with bound and gagged hostages and a bullet proof vehicle near the Arizona border.

A backlog of corpses.

Days after the massacre, the country's National Human Rights Commission announced that spiralling cartel wars have left a backlog of 30,000 unidentified corpses in trucks and morgues.

The number of murders in Mexico has soared in recent years. In 2018, there were 33,000 homicides which is a 33-percent increase on 2017, with 2019 expected to exceed that record.

Trucks that've been called by locals "morgues on wheels," sit in cities across Mexico - with residents increasingly complaining of the smell.

But it's not just drug cartels doing the killing, the country's security forces is believed to be involved in thousands of "enforced disappearances".

“Since 2006, enforced disappearances by security forces have been a widespread problem,” the Commission's report said, according to The Sun.