Fourteen Mexican soldiers were detained at the border in El Paso early Saturday after accidentally crossing into the United States, Customs and Border Protection said.
One soldier was cited for possessing marijuana for personal use, CBP said in a statement, and all were returned to Mexico within five hours.
CBP agents were on the Bridge of the Americas crossing in El Paso after midnight when they noticed Mexican military vehicles had crossed the international boundary, the agency said.
They detained the 14 soldiers who were inside the vehicles.
"The soldiers, weapons and equipment were secured for safety and processing," CBP said. "The soldiers advised that they did not realize they had entered the U.S."
Mexican military leaders were contacted and the soldiers and their equipment were returned to Mexico by 5 a.m., CBP said.
The Mexican Secretariat of National Defense did not immediately respond to a request for comment.
U.S. officials announced Friday that a camp with as many as 15,000 migrants had been cleared out. The area beneath a bridge in Del Rio, Texas, was the temporary home to Haitians who hoped they would be accepted into the United States.
CORRECTION (Sept. 28, 2021, 1:15 p.m. ET): A previous version of this article misstated which U.S. agency encountered the Mexican soldiers. They were agents of Customs and Border Protection, not the Border Patrol.