A 7-month-old baby survived a volley of gunfire unleashed by drug cartels in Mexico — thanks to one final, selfless act from her mother before the woman was killed.

Baby Faith was one of several survivors of the senseless violence in Sonora state Monday, when cartel members ambushed three cars packed with children and their mothers in a possible case of mistaken identity.

Hours after Christina Marie Langford Johnson, 29, was gunned down, relatives discovered her infant daughter Faith — unscathed and still strapped to her car seat inside the bullet-filled car.

“They found Christina’s baby Faith with the vehicle around her riddled with bullet holes. Somehow she had remained untouched, and alive,” wrote relative Kendra Lee Miller in a Facebook post Tuesday morning. “She was in her car seat, which looked to have been hurriedly placed on the floor of the vehicle by her mother for protection.”

In harrowing detail, Kendra wrote about the tragic moments three mothers and six children — all members of La Mora, a decades-old settlement in Sonora founded as part of an offshoot of The Church of Jesus Christ of Latter-day Saints — were killed amid a surge of violence in the remote area.

She said the three women — Christina, Rhonita “Nita” Maria Miller and Dawna Ray Langford — were traveling separately in three cars with 14 children between them when the gunfire broke out.

Christina and Dawna and their kids were traveling about 10 miles ahead of Rhonita and her crew when they were “fired upon from ahead,” said Kendra.

“Christina jumped out waving her arms to let the attackers know that it was women and children in the vehicles,” Kendra continued. “She gave her life to try and save the rest.”

But it was to no avail.

Dawna, 43, and her two sons, Trevor, 11, and Rogan, 2, were also shot dead, while her seven other children survived by jumping out and hiding in the bushes.

Many of the kids were later found by family members with gunshot wounds, including 8-month-old Brixon, who was shot in the chest and suffered a graze wound to the wrist, and 4-year-old Xander, who was shot in the back, Kendra wrote.

Meanwhile, gunmen also opened fire on Rhonita, 30, killing her and her four children — 8-month-old twins Titus and Tiana; Howard, 12; and Krystal, 10. Their bodies were burned beyond recognition.

“It appeared that one tried to escape as the front passenger door was open and the remains were partially in and out of the vehicle,” Kendra wrote in the post.

Rhonita’s husband, Howard, was in North Dakota at the time of the attack, while the couple’s three other children were being babysat by their grandparents, according to Kendra.

Two of the moms were en route to visit family in Chihuahua, while the third was headed to the airport in Phoenix, Arizona to pick up her husband, Kendra said.

“They never made it. They were ambushed by the Mexican cartels; shot, burned, and murdered in cold blood,” she wrote. “These were innocent civilians, American citizens simply trying to live peaceful lives.”