Another victim was identified online by family members as Christina Langford Johnson. "This is the time for Mexico, with the help of the United States, to wage WAR on the drug cartels and wipe them off the face of the earth. We merely await a call from your great new president!" López Obrador thanked Trump for the offer but said that "this is a matter of our sovereignty" and that Mexico would pursue the criminals. Mexican officials said that cartels might have mistaken the women's SUVs for those of rival traffickers. But relatives of the victims said the gunmen knew they were firing on civilians. "There's been a lot of rival cartels fighting up in this area," said Lenzo Widmar, one of the community members who found two of the destroyed vehicles. But he said that a child who witnessed the shooting recounted that one of the mothers got out of the vehicle and put her hands up when they were ambushed. "They shot her anyway," said Widmar. "They knew it was women and children."

More than 200 bullet casings were found near the vehicles, according to state authorities. Widmar said the group had not received threats lately. All the victims were residents of Mexico, he said. Another relative of the victims posted video of a charred vehicle in which a mother and her four children had been travelling. Loading Replay Replay video Play video Play video "This is how we live under the government of @lopezobrador," Alex LeBaron tweeted. "Mexican Mormons, innocent women and children were ambushed in the Chihuahua sierra, shot and burned alive by the Cartels that rule in Mexico!" Widmar said the attack occurred on Monday morning after the women left the community of La Mora, in northern Sonora state. One of them, Maria Rhonita LeBaron, was heading to Arizona to pick up her husband from the airport, he said. The other two women were going to accompany her as far as a main highway near the border, he said, and then head for the community of LeBaron, in nearby Chihuahua state. They were planning to attend a wedding there.

One vehicle, driven by Maria Rhonita LeBaron, had car trouble and the convoy returned to La Mora, he said. When the vehicles set out anew, LeBaron fell behind the other two women. LeBaron was just outside the village of San Miguelito when her Chevrolet Tahoe came under attack, according to a statement by Sonora state security officials. Assailants shot her and her four children -including 6-month-old twins, according to relatives and officials. The vehicle was then set on fire. Family members identified Dawna Ray Langford, pictured, as one of those killed in Mexico. About 17 kilometres east, toward the Chihuahua state border, authorities found the second vehicle, a white Suburban, with the bodies of a woman and two children, according to state officials. Relatives identified them as Dawna Langford and her three and 11-year-old children. Several other children escaped from the vehicle, they said. The third vehicle, also a white Suburban, was found about 1.5 kilometres east of the Chihuahua border. The body of a woman was found nearby. She was identified as Christina Langford Johnson.

Loading Another member of the clan, Julian LeBaron, said he discovered Christina's body and her infant when he reached her vehicle. "I found Christina. She was outside her car, face down, assassinated, and I found her baby, who was still alive," he told Ciro Gomez Leyva, host of a news show on Radio Formula. "I don't know if there's a war here or what's happening," LeBaron said. Johnson's cousin Leah Staddon, who used to live in La Mora and moved to Queen Creek, Arizona, said in a telephone interview that Johnson's six-month-old baby was found on the floor of the vehicle. "It's amazing because we first heard that she was dead also, then they found her alive," Staddon said.

One of the children is still missing. Five of the surviving children were flown to Tucson for treatment, said Staddon. "I think we're all still in shock, just trying to survive minute by minute," she said. The LeBarons describe themselves as Mormons but are part of a polygamous offshoot of the Church of Jesus Christ of Latter-day Saints. The attack came weeks after a botched anti-drug raid, in which Sinaloa Cartel gunmen seized control of the city of Culiacan after soldiers attempted to arrest the son of the notorious drug trafficker Joaquin "El Chapo" Guzman on a US extradition warrant. The government relinquished Ovidio Guzmán to avoid what it feared would be a bloodbath. The government was previously forced to hand over Ovidio Guzman Lopez, a son of Joaquin "El Chapo" Guzman. Credit:AP

"Hard to imagine that what happened in Sonora today won't impact [Mexico-US] relations and security policy in [Mexico]," wrote Falko Ernst, Mexico analyst for the International Crisis Group, on Twitter. "Over the next days, I'd expect pressure within the US to build on the Trump [administration] - by media and evangelicals, e.g. - and for that pressure to be passed onto Lopez Obrador." Loading Historically, Mormons began to settle in Mexico and Canada in the 1870s and 1880s to avoid being prosecuted by the US government because of the practice of polygamy, according to Matthew Bowman, a historian of the Mormon Church. After the main LDS Church, which has its headquarters in Utah, abandoned polygamy and began to crack down on the practice by excommunicating members, offshoot groups like the LeBaron family began to form in Mexico in the early 1900s. For decades, the LeBaron clan lived quietly in farming communities, maintaining close ties with the US and speaking both Spanish and English. But their relative wealth made them targets of extortion and kidnapping when organised-crime groups began to assert themselves in northern Mexico. In 2009, a prominent member of the clan, Benjamin LeBaron, 31, was shot dead near his community in northern Mexico. He had publicly denounced the drug traffickers, who had earlier abducted his younger brother, demanding a $US1 million ($1.4 million) ransom. (The family refused to pay). The killers left a message saying they were retaliating for LeBaron's activism.