Mexico – Mexican officials say gunmen who killed nine U.S. citizens — three women and six children — may have mistaken the group’s large SUVs for those of a rival drug gang.

Gen. Hector Mendoza, Mexico’s army chief of staff, said Wednesday that the attackers let some surviving children go, indicating that “it was not a targeted attack.”

Mendoza said the ambush consisted of two attacks, two hours apart at two places along the road. He said at 9 a.m. a Chevy Tahoe was hit by bullets and exploded in flames, and at 11 a.m., two Suburbans — one carrying the mother and her baby — were hit by gunfire.

The Americans were all living in northern Mexico.

The Juarez drug cartel and its armed wing, known as “La Linea,” or “The Line,” are fighting a vicious turf war against a faction of the Sinaloa cartel known as the “Salazar.”