MEXICO CITY (Reuters) – Fourteen Mexican soldiers were detained early Saturday morning for several hours by U.S. border agents after they crossed into El Paso, Texas, from Mexico’s Ciudad Juarez, the U.S. Customs and Border Protection (CBP)said.

CBP gave Reuters an emailed statement that it had observed two Mexican military vehicles cross the border into the United States just after midnight.

The 14 Mexican soldiers said they did not realize they had entered the United States and U.S. border agents secured their weapons and equipment for “safety and processing,” said the CBP, adding that Mexican military leadership was contacted and arrived at the port shortly thereafter.

Thirteen of the 14 Mexican soldiers were processed without incident, but one soldier was assessed a civil penalty after CBP officers discovered a personal use amount of marijuana in his possession.

The CBP stated that all fourteen soldiers were processed and returned their equipment and vehicles to Mexico within five hours.

Mexico’s Defense Ministry has not yet responded to our requests for comment.

Witness to the event said that the border crossing was shut down for approximately two hours due to the incident.

Witness, who did not want to be identified, said that CBP agents shouted at soldiers to drop their guns and put up their hands.

CBP agents searched and escorted the soldiers out of their vehicles. Reuters photos show that they appeared handcuffed.