AUSTIN, Tex. — Texas became the first state on Friday to deploy National Guard troops to the southern border of the United States after President Trump announced this week that he would send the military there.

State officials said 250 Texas National Guard personnel would be dispatched to the border within 72 hours. The mobilization began shortly after 7 p.m. Friday at the Armed Forces Reserve Center in Austin, as two light-utility Lakota helicopters carrying a total of four service members lifted off from the taxiway and flew south past a fading sun.

Brig. Gen. Tracy Norris, commander of the Texas Army National Guard, said the deployment would begin meeting “the priorities of the governor and the president in securing our border.” In addition to troops, the Guard said it would send ground surveillance vehicles and light and medium aircraft.

The announcement in Austin came the same day that the Republican governor of Arizona, Doug Ducey, said that about 150 members of the National Guard in his state would deploy next week to the border. Other governors have weighed in as well, with their support or criticism of the plan falling along party lines. The Republican governor of New Mexico, Susana Martinez, vowed to send troops soon, while the Democratic governor of Montana, Steve Bullock, refused.