Illegal crossings continue in Starr County.

A group of four migrants were released by a human smuggler in Roma Thursday night.

As soon as they stepped on U.S. soil, Border Patrol took them into custody.

Channel 5 News followed the Texas National Guard to see how they conduct their operations.

"We're looking for drugs, we're looking for weapons, we're looking for human trafficking that doesn’t want to be caught to include sex trafficking and we're also looking for high value individuals that the law enforcement agencies are looking for," said Major Michael Perry.

Major Perry says that these encounters happen mostly at night and, sometimes, they can apprehend up to 200 migrants in this area of the border.

The National Guard says they are using high definition technology to identify migrants making their way across the river in the darkness.