Nine US citizens, three women and six children, were killed in an attack by suspected drug cartel gunmen in northern Mexico on Monday.
Officials have not named the victims, but family members have identified those killed as members of the LeBaron family.
The victims are reportedly all dual US-Mexican citizens who live in a community which broke away from the mainstream Mormon Church and settled in Mexico nearly a century ago.
The motive for Monday's attack remains unclear - though officials have speculated it may be a case of mistaken identity.
'Driving together for safety reasons'
The attacks happened near the town of Bavispe in the state of Sonora, which borders the US.
Family members said three mothers were travelling with their 14 children in three separate vehicles when they were ambushed.
Kendra Lee Miller, whose sister-in-law Rhonita Maria Miller died in the attack, told CNN the group had separate destinations but were driving together for safety reasons.
Ms Miller said Rhonita, 30, was travelling with four of her seven children to pick up her husband in Arizona, where he had been working. The couple's other children were reportedly being cared for by grandparents.
At some stage the car Rhonita departed in broke down, Ms Miller said, so the three women turned back to get another and set off again.
Rhonita's second car, which had reportedly been behind the others, was then set upon by unknown gunmen. At some point, that car caught fire and exploded.
All five inside were killed. Footage from the aftermath showed the car burned out and covered in bullet holes.
"My dad Andre and couple of uncles and relatives went to check up on the vehicle. All they found was charred remains, ash and bones," Ms Miller told CNN.
The youngest victims, Titus and Tiana, were eight-month-old twins. Two of Rhonita's other children in the car - a 12-year-old named Howard and a 10-year old called Krystal - also died, Ms Miller said.
The other victims, in their two vehicles, were also set upon further along the road, police and family said.
Christina Marie Langford Johnson, 31, died in a second vehicle.
Family members said her seven-month-old daughter, Faith, was later found uninjured in her car seat on the floor of the vehicle. In social media posts, the family said they believed her mother had moved her to safety.
Ms Miller said Dawna Ray Langford, 43, was killed in the third vehicle along with her two sons, Trevor and Rogan, who were aged 11 and three.
Seven of her other children, aged between 9 months and 14-years old, who were also in the car managed to escape and were recovered later, family said.
Five of them were shot or sustained other injuries. Some of the older children helped hide the group and they were later found by search parties and taken by ambulance to a local hospital, according to Ms Miller.
Ms Miller says the children were then evacuated in a military helicopter and were transferred to Arizona for further treatment.
Relatives say the bodies of the deceased have been taken back to their family ranch.
"It was a massacre," Julian LeBaron, a family member and anti-violence activist, told Mexican media.
'A massive family'
A GoFundMe page for the victims describes the community as living between the US and Mexico.
Family members told CNN the community in which they live has about 3,000 members.
Tiffany Langford, related to the victims, told the news website that members of the group had a variety of beliefs, but generally the community practised fundamentalist Mormonism.
"We are a massive family," Ms Langford told CNN.
"We love and support each other no matter what our individual beliefs. I've never seen such a strength of unity and love in a family as large as ours. This is the tragedy of our lives."