A South Texas school district is warning parents that U.S. Border Patrol agents may be checking the immigration status of students as they participate in extracurricular activities. On Wednesday, the Alice Independent School District sent out a letter alerting parents that agents may be boarding school buses to question students about their citizenship status.

Texas Gov. Greg Abbott deployed the troops to the Rio Grande Valley, where he said they'll work side-by-side with U.S. Border Patrol agents to keep migrants from illegally entering the country. Some of those troops left from the U.S. Naval Air Station Joint Reserve Base in Fort Worth Monday morning. The others left from a base in Houston.

A line of Mexican National Guard and Army trucks rumbled along the border separating Ciudad Juárez and El Paso, Texas, on Wednesday, among the first of 10,000 troops Mexico has sent to its northern frontier following tariff threats by President Donald Trump.

The new policy is a result of a memorandum of understanding between Texas Gov. Greg Abbott and the head of U.S. Customs and Border Protection.