The “steel wall” of cars, as Abbott called it, is only the latest of the stark images coming from the crisis unfolding in Del Rio, Tex., where nearly 15,000 border crossers, many Haitians living in Chile and other South American nations, have arrived.

The Homeland Security Department is investigating reports that Border Patrol agents on horseback attempted to grab migrants and push them back toward Mexico, captured in scenes Sunday along the Rio Grande.

“What we did, we put hundreds of Texas Department of Public Safety cars and created a steel wall — a steel wall of DPS vehicles — that prevented anybody from crossing that dam that you’ve seen people walk across,” Abbott told Fox News in an interview Tuesday. “We effectively … regained control of the border.”