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

The dead included 8-month-old twins. Eight youngsters were found alive after escaping from the vehicles and hiding in the brush, but at least five had gunshot wounds or other injuries and were taken to the U.S. for treatment, officials said.

One woman was killed after she apparently jumped out of her vehicle and waved her hands to show she wasn’t a threat, according to family members and prosecutors.

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

The bloodshed took place Monday in a remote, mountainous area in northern Mexico where the Sinaloa cartel has been engaged in a turf war. The victims had set out to visit relatives in Mexico; one woman was headed to the airport in Phoenix to meet her husband.

While a drug-related violence has been raging for years in Mexico, the attack underscored the way cartel gunmen have become increasingly unconcerned about killing children as collateral damage. Around the ambush scene, which stretched for miles, investigators found over 200 shell casings, mostly from assault rifles.

“Lately it’s getting worse. This is a whole new level,” said Taylor Langford, a relative of the dead who splits his time between the Mexican community and his home in the Salt Lake City suburb of Herriman, Utah.

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

The victims lived in Sonora state, about 70 miles (110 kilometers) 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 the 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.

Prosecutors said the woman who waved her arms, Christina Langford Johnson, was found 15 yards (meters) away from her Suburban van, shot to death. Her 7-month-old daughter, Faith Marie Johnson, was discovered uninjured in her car seat.

Kendra Miller, a relative, wrote that the baby’s car seat “seemed to be put on the floor by her mother to try and protect her. … She gave her life to try and save the rest.”

A short distance away, Dawna Ray Langford, 43, lay dead in the front seat of another Suburban, along with the bullet-riddled bodies of her sons, ages 11 and 2.

Of the children who escaped, one had been shot in the face, another in the foot. One girl suffered gunshot wounds to her back and foot.

Cowering in the brush, one boy hid the other children and then walked back to La Mora to get help. Another girl, who was initially listed as missing, walked off in another direction, despite her gunshot wounds, to get help.

A group of male relatives set out to try to rescue the youngsters but turned back when they heard gunfire ahead.

A relative of the dead who did not want his name used for fear of retaliation said in an interview that when they finally made it to the scene where the ambush started — about 11 miles (18 kilometers) from where the two other mothers were killed — they found a burned-out Chevy Tahoe.

Inside, they saw the charred remains of Rhonita Miller, 30, her 10-year-old daughter, a son, 12, and her 8-month-old twins. They were “burnt to a crisp,” the relative said.