Nine members of a US Mormon family have been killed in Mexico.
Three mothers and six of their children were executed by a drug cartel in what is believed to be a case of mistaken identity.
Many more children were wounded in the attack, while up to a dozen more family members have been reported missing.
All the victims were US citizens and members of La Mora, a Mormon settlement around 70 miles south of the Arizona border, USA Today reported.
The ambushes struck as three separate SUVs were travelling about eight miles apart between the states of Chihuahua and Sonora, both of which border the US.
The gunmen disabled the cars with bullets, even causing one of them to explode.
Rhonita Maria LeBaron, 33, was killed along with her 12-year-old son Howard, ten-year-old daughter Krystal and twin six-month-old babies Titus and Tiana. Dawna Ray Langford, 43, died alongside her two children Trevor, 11, and Rogan, three. Christina Langford Johnson, 29, was also shot dead; her seven-month-old daughter Faith was found alive on the floor of the car.
One relative, Leah Langford-Staddon, sent an urgent message on Facebook looking for help, saying: “3 vehicles with my family members in them were traveling this morning from Sonora to chihuahua and they were ambushed by the mafia. My nephews wife and 4 children were shot and burned in their vehicle, and the rest, 2 women and 10 children were kidnapped.
“They are doing all they can in Mexico and we need America’s help. Please help get the word out. We need to get them all back home safe. also do not travel to Mexico! The mafia over Sonora and the mafia over chihuahua are in all out war right now!!!”
President Donald Trump said it was time to declare war on Mexican drug cartels.
“A wonderful family and friends from Utah got caught between two vicious drug cartels, who were shooting at each other, with the result being many great American people killed, including young children, and some missing,” he tweeted. “If Mexico needs or requests help in cleaning out these monsters, the United States stands ready, willing & able to get involved and do the job quickly and effectively.
“The great new President of Mexico has made this a big issue, but the cartels have become so large and powerful that you sometimes need an army to defeat an army!”