A Mexican official says some Mexican nationals were among the survivors and those who died on a tractor-trailer found at a San Antonio Walmart.
Mexican Consul General in San Antonio Reyna Torres says officials are working to identify the survivors and notify family members. Torres says the consulate has been in contact with relatives both in Mexico and the U.S.
Guatemala's foreign ministry, meanwhile, says at least two Guatemalans were on the abandoned rig.
Tekandi Paniagua, communications director for the foreign ministry, says the two male survivors told Guatemalan consulate officials that they crossed the border by foot at Laredo and boarded the tractor-trailer. They told officials their final destination was Houston.