■ A monument was inaugurated to honor nine U.s.-mexican citizens killed in an ambush.

MEXICO CITY — Mexican President Andrés Manuel López Obrador inaugurated a monument Thursday to the memory of nine U.s.-mexican dual citizens ambushed and slain on Nov. 4, 2019, possibly by drug gang assassins.

The monument in the small town of La Mora is in the northern border region near New Mexico, near the site where the groups was ambushed along a rural road.

Sonora state Gov. Claudia Pavlovich said the monument “is a testament to the need that this never be forgotten, that this always be remembered, and that it never be repeated.”

The killings of three women and six children from the extended Langford, Lebarón and Miller families shocked Mexico.

Amber Ray, the sister of victim Dawna Ray Langford, said the monument was “a reminder that, even in a time of great tragedy, we can unite and defend ourselves against violence.”

Investigations suggest that a squad of gunmen from a drug gang that originated in the border city of Ciudad Juarez set up the ambush to kill members of a rival cartel. But relatives of the victims say that at some point, the gunmen must have known who they were killing.

Mexican authorities say that 17 suspects have been arrested and that 15 more arrest warrants for other suspects have been issued.

López Obrador said the killings showed the need to offer young people in Mexico education or job opportunities, so they would not be recruited to drug gangs. In the meantime, he said, “we are going to continue (with investigations) until the whole truth comes out, and justice is done.”