MEXICO CITY (AP) — Drug cartel gunmen ambushed three SUVs along a dirt road, slaughtering at least six children and three women — all of them U.S. citizens living in northern Mexico — in a grisly attack that left one of their vehicles a burned-out, bullet-riddled hulk, authorities said Tuesday.

The dead included 8-month-old twins. At least five other youngsters were wounded by gunfire.

Mexican Security Secretary Alfonso Durazo said the attackers may have mistaken the group’s large SUVs for those of rival gangs.

But all of the victims were believed to be members of the extended LeBaron family, who live in a decades-old settlement founded by an offshoot of The Church of Jesus Christ of Latter-day Saints and have run afoul of the drug traffickers over the years. A LeBaron was killed a decade ago after denouncing the cartels.

The mafia vehicles got her and four of her kids and … burnt them to a crisp

In a tweet, President Donald Trump immediately offered to help Mexico “wage WAR on the drug cartels and wipe them off the face of the earth.” But Mexican President Andrés Manuel López Obrador rejected that approach, saying his predecessors waged war, “and it didn’t work.”

A relative said the victims lived in the hamlet of La Mora in Sonora state, about 70 miles (110 kilometers) south of Douglas, Arizona. A number of extended Mormon families live in farming communities clustered around the Chihuahua-Sonora state border. Many members were born in Mexico and thus have dual citizenship. While some of the splinter groups were once polygamous, many no longer are.

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The group was attacked Monday while traveling in a convoy of three SUVs toward Pancho Villa, in Chihuhua. The relative asked not to be named for fear of reprisals.

The relative said he had located the burned-out SUV containing the remains of his nephew’s wife and her four children — the twin babies and two other children. Authorities said the Chevy Tahoe’s gas tank had apparently been hit by gunfire and exploded.

“The mafia vehicles got her and four of her kids and … burnt them to a crisp,” said the relative.

Two women and two other children were later found dead.

The six children killed were 8 months old, 2½, 10, 11 and 12, according to family members.

“The United States stands ready, willing & able to get involved and do the job quickly and effectively,” Trump tweeted. “The great new President of Mexico has made this a big issue, but the cartels have become so large and powerful that you sometimes need an army to defeat an army!

But Mexico’s president said: “The worst thing you can have is war.”

It was the second failure in recent weeks for López Obrador’s “hugs not bullets” anti-crime strategy. Two weeks ago, Mexican forces seized a son of the imprisoned drug lord known as El Chapo but had to release him after cartel henchmen launched a furious counterattack in Culiacan, Sinaloa.

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The prosecutor’s office in Sonora state gave a description of the crime scene on the Sonora-Chihuahua border. They said police first found the burned-out Chevy Tahoe with the five dead. About 11 miles (18 kilometers) up the mountainous dirt road, they found a Suburban with a dead woman and two dead children inside. Farther on, they found a second Suburban and, about 15 yards (meters) away, the body of a woman.

Police found a total of about 200 spent shell casings from assault rifles and other weapons at the various crime scenes.

“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,” Trump wrote.

The relative said: “We’re guessing right now, but we believe it was a case of mistaken identity. They just opened fire on the vehicle because it was an SUV.”

Durazo said the Sinaloa cartel had an important presence on the Sonora side, but that a rival gang was trying to invade the territory from the Chihuahua side.

The relative said he saw cartel gunmen gathered about a mile away after the ambush. “There were probably 50 or 60 of them, armed to the teeth,” he said.

A suspect was detained near Agua Prieta, the prosecutor’s office said, but it was unclear whether the person had taken part in the ambush. The suspect had assault rifles and a .50-caliber sniper rifle and was holding two bound kidnap victims, authorities said.

It was not the first time that members of the breakaway church had been attacked in northern Mexico. In 2009, Benjamin LeBaron, an anti-crime activist who was related to those killed on Monday, was slain in 2009 in Chihuahua state.