Many of the nine women and children killed on a remote stretch of highway in northern Mexico Monday were shot at point-blank range — victims of a targeted assassination that Mexican authorities refuse to allow their American counterparts to investigate, according to high-ranking Mexican and US law enforcement sources.

“They were taken out of their cars and shot,” an American federal investigator told The Post. “It’s kind of disturbing that the FBI has had no access to the crime scene, which is probably a disaster already because the Mexicans have allowed families to remove the bodies. Any evidence that could have been gathered is probably destroyed.”

The Mexican federal official close to the investigation told The Post that the sicarios “shot some of the victims at point-blank range” and that local authorities were still gathering evidence at the scene in Sonora state, some 70 miles from the Arizona border, where the massacre occurred.

The revelations run completely counter to the official accounts the Mexican government put out, which blamed the deaths of three mothers and six young children — including 8-month old twins — on cartel gunmen who mistook the Mormons’ convoy of dark SUVs for a rival drug group’s.

Army chief of staff Hector Mendoza told a press conference that a faction of the Juarez Cartel, La Linea, thought their Los Salazar rivals — in the Sinaloa Cartel, once headed by Joaquin “El Chapo” Guzman — were encroaching. Mendoza said that the two criminal groups had clashed a day before the massacre in the same region. Mendoza said that the attackers even allowed some of the surviving children to go, indicating that “it was not a targeted attack.”

But both sources said Mexican officials were covering up the savage attack’s true targets.

“We’ve been saying all along that the Mexican government just doesn’t want to investigate anything related to drug trafficking,” said the American federal source, adding that officials in Sonora state sought FBI help for the massacre probe but were thwarted by Mexican federal officials.

“They will go to any extreme to cover everything up,” said the US source. “It’s completely corrupt, and it’s only going to get worse.”

On Saturday, an FBI spokesman offered only this comment when asked if it was being obstructed by Mexican authorities: “The FBI continues to engage with our US government and Mexican law enforcement partners. We have offered assistance and stand ready to assist in the wake of this tragedy.”

Some members of the victims’ families who were part of a tight-knit group of Mormon communities in the neighboring states of Sonora and Chihuahua said they don’t believe the government’s official version of events.

“They [the hitmen] had to know that these were women and children,” said Julian LeBaron in an interview with “El Universal” in Mexico. He told the newspaper that some of the eight children who survived the massacre said that one of the mothers left her truck with her hands up in the air when she was shot and killed.

Christina Marie Langford Johnson, 29, was fatally shot in the chest when she jumped out of her Chevy Suburban and waved at the shooters to try to get them to stop. Before leaving the vehicle, she placed her 7-month-old daughter Faith’s car seat on the SUV’s floor, likely saving the child’s life.

The brave mother was buried on Saturday, her plain pine casket surrounded by members of the Mormon communities and relatives of the extended Le Baron family. Her husband, Tyler Johnson, was seen holding a young boy during the service in LeBaron, Chihuahua, Mexico.

The victims, dual US-Mexican citizens, all had links to the prominent LeBaron and Langford families in several small Mormon farming communities that have a long history of violent clashes with local drug traffickers.

“This is a very high-risk zone for confrontations with cartels,” said the Mexican source, adding that both the Sinaloa and Juarez cartels use the remote roads to transport drugs to the Arizona border.

Mormons began settling in the region after 1890 when the US government began to put restrictions on polygamy. The community is fundamentalist but has no leader and is not affiliated with the Church of Latter Day Saints in Utah. Many in the community still practice polygamy.

Although it’s not yet clear what might have provoked last week’s massacre in which three SUVs traveling in a convoy between Sonora and Chihauhua states were attacked by a hail of bullets and engulfed in flames, the prosperous Mormon farmers and ranchers in the rugged, mountainous region have long been vocal opponents of drug traffickers, and have resisted attempts by the criminal groups to extort them in the past.

In 2009, Julian LeBaron’s older brother, Benjamin, a local farmer and activist founder of a crime-fighting group called SOS Chihuahua in Colonia LeBaron, was killed by traffickers after he led protests over the kidnapping of their 10-year-old brother, Eric, who was being held for $1 million in ransom by local drug traffickers. Colonia LeBaron was founded in 1924.

The family refused to pay the ransom and Eric was eventually released, but Benjamin and a neighbor — Luis Widmar — were killed when 20 heavily armed men invaded the LeBaron home and shot both men dead.

“These are not isolated incidents,” said Julian LeBaron, in a 2010 opinion piece in a Dallas newspaper. “Throughout our nation, countless people have lost their lives or their security in a similar manner, while politics of confusion and volumes of magic words appear to have more sway than reality.”

The massacre has come on the heels of other violent confrontations between traffickers in Mexico, which has already recorded more than 32,000 homicides since December. Last year’s total was 33,341 homicides, most of them related to drug violence, according to Mexico’s Ministry of the Interior.

Last month, an elite group of state police officers on a routine patrol in Culiacan, in northern Mexico, captured one of El Chapo’s sons. But when a fierce gun battle erupted around them, killing two people and injuring 21, security forces released Ovidio Guzman Lopez. Last week, the 30-year-old officer who detained Guzman Lopez, was ambushed and killed in a hail of more than 150 bullets in Culiacan.

Since coming to power last year, Mexican president Andres Manuel Lopez Obrador’s security strategy has been to emphasize “hugs not bullets” to combat drug-related violence in the country.

“It was lamentable, painful because children died, but do we want to resolve the problem … by declaring war?” said Lopez Obrador last week in response to the Mormon massacre.