Transcript for Mexican ambush that killed 9 Americans: What we know
llamas is in Mexico. Reporter: Horror in a remote Mexican town. Nita and five of my grandchildren are burnt, shot up. Reporter: This is the aftermath of a brutal massacre that claimed the lives of three American women and six children, including eight month old twins Titus and tee Anna. I believe they were just in the wrong place at the wrong time. Reporter: They were traveling with their children in three separate vehicles. 17 people in all. The family had plans to celebrate a wedding this weekend. Traveling south of the U.S. Border. This is narco territory. Mexican officials believe they were caught in the cross hairs of cartel violence, saying that a criminal gang confused them with a group aligned with the sinaloa cartel. More than 200 rounds were fired at the women and children. Miraculously, some of the children survived, like Christina Langford's baby. After hours and hours of being alone by herself in the car, they were able to find her. Reporter: One of Christina's relatives showed us this video of when baby faith was found. I walked around the vehicle and opened the door, and there was a car seat. And there was a bullet hole through the canopy on the car we opened the canopy, and the baby was smilin' at us. Reporter: One of the vehicles was burned. The remains of ro Nita Miller and her children inside. There's no way you can wrap your head around it. Reporter: One of the reasons the drug cartels are prevalent is because it's remote. It's not too far from the border. But getting here is difficult. There are never-ending winding roads. The families belonged to a fundamentalist Mormon community. They had dual citizenship in the U.S. And Mexico. I think I'm still in shock that something like this happened to my family, like these are things I see in movies, not in life. Reporter: Relatives say at one point, Christina got out of her vehicle with her hands up, but the gunman shot her anyway, point blank in the chest. Eight children survived. Some thanks to 13 year old Devon Blake Langford who was able to save several siblings who had been shot. He hid them in a bush on the side of the road, told them to stay, and he ran all the way back home. I think they said it was like ten or more miles that he walked. Reporter: Those rescued children were taken vie yeah helicopter to a hospital in Mexico. Kendra is the sister-in-law. It was her wedding the families were planning to celebrate this weekend. I really can't say enough how horrified I am and we all are at these people that, I mean, that they could commit such horrible atrocities. Reporter: President trump tweeting if Mexico needs or wants help in cleaning out these monsters, the United States stands willing, ready and able to get the job done quickly and effectively. But Mexico's president says they will handle this alone, vowing I would love for someone to be held accountable. But I don't know that that's going to happen. Reporter: Mexican authorities are honing in on a criminal group. One of the experts we spoke to say the closest military base is three hours away, and there aren't too many police officers to guard this area, and that's why the cartels feel they can run rampant and do whatever they a family member in Arizona says she's afraid to travel to Mexico for the funerals. It's devastating that I can't even be at this funeral for my loved ones. Because of the dangerous situation. Reporter: Mormons have a long history in Mexico. Christina Rossetti studies the religion. In the 1890s, mormons began traveling to Mexico to practice polygamy. Reporter: Most that do aren't affiliated with the lds church in the U.S. Mormonism has split into different factions and communities. A lot of people have relatives who were at one point in the Mexican colonies. And that includes even Mitt Romney. Reporter: This week's violence isn't the first time this family has faced horrible situations as a result of the drug wars. In 2009, a man named Benjamin labaron was murdered by a cartel. Reporter: He was an anti-crime activist, killed by a gang of armed men. His brother spoke to the associated press about the increasing cartel violence. They're all going to be buried in Mexico? Reporter: We caught up with Julio as he mourns this new loss. Did you ever think the violence would reach this level? Not really. I don't think anybody can imagine. What kind of men can call themselves men that murder women and children? There's been some talk amongst my uncles, amongst my family living here of thinking about moving out. It's starting to escalate. Reporter: According to justice in Mexico, a research initiative, about a third to half of Mexico's homicides since 2006 can be attributed to organized crime groups, especially drug trafficking organizations. Cartels have such a strong presence, it's especially dangerous for Americans to go in as tourists. Reporter: Last month, Mexican security forces were outgunned by a drug cartel. This body cam shows them pleading with the son of el Chapo. They're like the government of Mexico, sometimes more powerful than the government. We saw a recent example where el Chapo's son was released because they feared violence. Anytime a government relents and basically says to the bad guys, you're the ones in charge, that's a big problem. Reporter: Last year, my colleague Dan Harris spent time embedded with the sinaloa cartel. They are largely in control. Dan met with the men who believe they are true authorities here. So they are pretty eager to show how well-armed they are. See, that's a grenade. Reporter: They showed off their weaponry, much of it American made. Off to the side, the commander gave Dan bracing insights as to what his job actually entails. Just to be clear, your job entails killing people sometimes. Reporter: Yes, he says. Does that take a toll on you psychologically? Reporter: He says the first time it did, but not anymore. I'll never forget the first time. Reporter: The Mexican government has broken up many of the cartels. But that has only fueled the skyrocketing violence with smaller gangs competing to fill the vacuum. Every couple years, the Mexican police find mass graves, hundreds of people buried. There's more mass graves out there of people who are just forgotten victims of the drug war. Reporter: Violence that is a cost for all too many families having to say good-bye to loved what's your message to the cartels? To the cartels? Honestly, I don't have a message for the cartels, but I do have a message for the Mexican people, there's 120 million of us. We have had so much violence in we need to come together and stop being divided by politics. Reporter: For "Nightline," Tom llamas in northwest Mexico.
This transcript has been automatically generated and may not be 100% accurate.