A heavily armed suspected drug lord has been arrested and is under investigation for the slaughter of nine Americans, including three mothers and six children, after the Mormon family was ambushed in northern Mexico by cartel gunmen.

The suspect – only identified as Pablo – was found late Tuesday in the town of Agua Prieta, right at the border with the U.S. state of Arizona, holding two hostages who were gagged and tied inside a vehicle, Mexico’s Agency for Criminal Investigation said.

Authorities said the suspect was also found in the possession of four assault rifles and ammunition, as well as various large vehicles including a bullet-proofed SUV.

The hostages are not believed to be related to the nine LeBaron family victims who were killed on Monday while traveling in a convoy of three SUVS on a dirt road in Sonora state.

Devastated family members of the slain victims visited the scene of the grisly murders late on Tuesday and were pictured sobbing as they saw the burnt out and bullet riddled SUVs.

Investigators are still trying to determine if the arrested suspect is connected to the brutal slayings.

Officials have said that the cartel gunmen may have mistaken the group’s large SUVs for those of a rival gang amid a vicious turf war.

The killers were apparently members of the Juarez drug cartel and its armed wing, La Linea – ‘The Line’ – whose gunmen had entered Sinaloa cartel territory and set up an armed outpost on a hilltop and an ambush further up the road.

The Sinaloa cartel was previously headed by Joaquin ‘El Chapo’ Guzmán. The area where the attack occurred is dominated by a Sinaloa cartel offshoot called the Jaguars.

The Juarez cartel apparently wanted to send a message that it controlled the road into Chihuahua. It was this invasion force that the American mothers and their three vehicles drove into.

It was only after the first vehicle was shot up and set afire that 50 or 60 Sinaloa cartel gunmen showed up to see what had happened.

The mothers were driving in separate vehicles with their children from the La Mora religious community where they live, which is a decades-old settlement in Sonora state founded as part of an offshoot of The Church of Jesus Christ of Latter-day Saints.

Rhonita Miller and four of her children – her six-month-old twins, Titus and Tiana, her 10-year-old daughter Krystal and 12-year-old son Howard – were all killed.

Another two mothers, Dawna Langford and Christina Langford Johnson, as well as Dawna’s sons, Trevor, 11, and Rogan, 3, were also all killed.

Eight children, some just infants, survived the ambush.

Those surviving children not only escaped the drug cartel gunmen who killed their mothers but managed to hide in the brush for hours until help arrived.

Dawna’s 13-year-old son Devin covered his injured siblings with branches to hide them before walking 13 miles to get help from relatives back at La Mora.

Relatives say he reached the community six hours later. Family members alerted authorities before arming themselves with guns to go out searching for the injured children.

The five wounded children were seriously enough injured that Mexican authorities flew them to the border in a military helicopter to receive hospital care in the United States. Sonora state health officials said they were ‘stable’ at the moment of transfer.

Three other children who were not wounded are in the care of family members in La Mora.

In the aftermath of the tragedy, harrowing details emerged of the attack including how a quick-thinking Christina managed to save her children’s lives.

Christina stashed her seven-month-old baby Faith on the floor of her Suburban and got out of the vehicle, waving her arms to show the gunmen she wasn’t a threat.

She may have moved away from the vehicle to distract their attention because her bullet-ridden body was found about 15 yards away from the SUV.

The baby was found unharmed and still in her car seat on the backseat floor of the SUV when family members arrived at the scene hours later.

She has since been reunited with her father Tyler Johnson.

What the children went through in the remote, mountainous area of Sonora state is nearly indescribable.

Kendra Miller, a relative, said in an account of the shootings that Devin Langford, 13, was one of the few uninjured young people and quickly took charge, eventually walking about back to La Mora for help.

‘After witnessing his mother and brothers being shot dead, Devin hid his six other siblings in the bushes and covered them with branches to keep them safe while he went for help,’ according to the account.

‘When he took too long to return, his 9-year-old sister left the remaining five to try again.

That girl, McKenzie Rayne Langford, walked for hours in the dark before she was found several hours after the other children were rescued. She was listed as missing for a while.

Altogether, the kids were on their own from about 1pm, when the ambush began, until about 7.30pm, when they were rescued.

Relatives from La Mora tried to reach them before that, but were turned back by gunfire. The area is the site of a cartel turf war.

In recordings of calls between the rescuers, they can be heard debating whether it was better to risk more lives, or wait for an hour or two until Mexican army troops arrived. It was an agonizing decision.

What they saw when they found the children was terrifying.

Dawna’s eight-year-old son Cody Greyson Langford had been shot in the jaw and leg. Her 14-year-old daughter Kylie was shot in the foot and four-year-old Xander was shot in the back.

Brixon, a nine-month-old, suffered a gunshot wound to the chest. Her son Jake was found injured in the same spot but it’s not clear what his injuries are.

But it isn’t the cruelty of the cartel, but the bravery, innocence and sacrifice of the victims that relatives want remembered.

Austin Cloes, a relative of the victims, said from his home in Salt Lake City that they were good people who loved their children and enjoyed their quiet lives based around a successful pecan farming operation.

‘This sort of thing shouldn’t go unnoticed,’ said Cloes, who works with at-risk youth and coaches high school basketball.

‘And these sorts of people shouldn’t just be buried without their names being put out there. These are great people.’

The victims lived in Sonora State, about 70 miles south of Douglas, Arizona, in the hamlet of La Mora, which was founded decades ago by an offshoot of The Church of Jesus Christ of Latter-day Saints.

Many La Mora residents call themselves Mormons but are not affiliated with any church.

A number of such American farming communities are clustered around the Chihuahua-Sonora state border. Many members were born in Mexico and have dual citizenship. While some of the splinter groups were once polygamous, many no longer are.

All of the victims were apparently related to the extended LeBaron family in Chihuahua, whose members have run afoul of the drug traffickers over the years.

Benjamin LeBaron, an anti-crime activist who founded neighborhood patrols against cartels, was killed in 2009.

The victims had set out from their home in three SUVS.

Family members say Rhonita was driving to Phoenix, Arizona with her children to pick up her husband at the airport following his work trip.

Christina and Dawna were each traveling with their own children and were en route to see family in the state of Chihuahua for a wedding that was scheduled for Friday, relatives told DailyMail.com.