A U.S. law enforcement officer on horseback wielded what appeared to be a lariat, whipping it close to the face of a man wading in the Rio Grande carrying a plastic bag of food.

It was just one desperate moment in a few hours of such scenes along the Rio Grande on Sunday.

Hundreds of Haitian migrants who have been camping under a bridge in the Texas town of Del Rio were trying to bring food and other supplies from Ciudad Acuna in the Mexican state of Coahuila, while U.S. officials have stepped up security at the border and started flying migrants out of the area, some to Haiti.