A mother and her son from Kansas were shot to death in Juarez, Mexico last Friday.

35-year-old Rosa Williams and her son, 19-year-old Pablo Noe Williams, were riding in an SUV with two other people when gunmen attacked their vehicle.

Using assault rifles, the attackers shot up the vehicle, killing all four inside.

U.S. Consulate officials in Juarez haven’t released where Williams and her son were from in Kansas.

Mexican officials don’t have a motive for the deadly shooting.