More than 500 chairs were arranged in neat rows for the mourners, who traveled in convoys from both sides of the Mexico-U.S. border for the first funeral on Thursday, for Dawna Ray Langford, 43, and her sons Trevor and Rogan. Their bodies lay in simple wooden coffins constructed by family members.
Kenneth Miller, a relative of several of the victims, all of whom were dual U.S.-Mexican citizens, said the family hoped their plight would draw attention to the thousands of victims whose cases go unsolved as violence reaches record levels in Mexico.
"You can't imagine that there are people who could do such a horrible thing like this, innocent women, innocent children," he said, fighting back tears.
Members of breakaway Mormon communities that settled in Mexico decades ago, Langford and two other women and six children were ambushed in Sonora state on Monday, leading U.S. President Donald Trump to urge Mexico and the United States to "wage war" together on the drug cartels.
Another event honoring the victims was to take place later on Thursday.
"We came prepared to sleep on the floor, in tents. Whatever is needed to support the families who died in this terrorist act," said Alex LeBaron, a former Mexican congressman and cousin of one of the women, Rhonita Miller.
Miller and her children, whose bodies were reduced to ash and bones when the car they were in was shot at and then went up in flames, are due to remembered in a ceremony in an another village, Colonia LeBaron, on Friday.
Alex LeBaron, who was with Thursday's convoy, told Mexican radio that mourners had come from the United States and across Mexico, bringing food and mattresses for the journey.
The LeBaron family, which came to Mexico in the early 20th century, claims to now have more than 5,000 members.
Authorities and relatives say the killings appeared to be the work of the Juarez and the Sinaloa cartels, which fight for control of lucrative drug routes that run through the sparsely populated mountainous areas into the United States.
Mexico has unleashed its military against cartels since 2006, but despite the arrests or killings of leading traffickers, the campaign has failed to reduce violence. Instead, it has led to more killings as criminal groups fight among themselves.
The victims came from prominent local families, including the LeBarons, Millers and Langfords.
Nestled in the fertile valleys of the Sierra Madre mountains just a few hours drive south from the U.S. border, the oldest communities stem from the late 1800s, when upheaval over polygamy in the Utah-based church led to their founding.The settlements have marriage ties to others in the United States.