EAGLE PASS, Texas — In one large group, more than 300 migrants crossed the Rio Grande Sunday as temperatures exceeded the 100-degree Fahrenheit mark. As Border Patrol and Texas Highway Patrol Troopers managed nearby traffic, many migrants pleaded for water.

The group consisted of mostly single adults from Cuba, Venezuela, Nicaragua, and the Dominican Republic. Breitbart Texas spoke to several who said they had been traveling for at least four months. Ambulance crews arrived on the scene to treat those affected by heat exhaustion.

One migrant said many in the group spent longer than two months in Tapachula, Chiapas, waiting for the Mexican immigration services to issue refugee status and travel documents.

The Border Patrol’s Del Rio Sector on most days leads the nation in migrant apprehensions, according to a source within Customs and Border Protection. The traffic creates a constant struggle for overcrowded processing facilities in the area.

The CBP source, who is not authorized to speak to the media, told Breitbart Texas that more than 160,000 migrants have crossed into the United States in June with the vast majority arriving in Texas-based sectors.

As authorities worked to transport the large group to a nearby Border Patrol processing center, Breitbart Texas witnessed several smaller parties crossing near downtown Eagle Pass. The large groups, sometimes numbering more than 400, are more taxing to the agency’s resources but constitute only a portion of the Border Patrol’s apprehensions in the city.

Randy Clark is a 32-year veteran of the United States Border Patrol.  Prior to his retirement, he served as the Division Chief for Law Enforcement Operations, directing operations for nine Border Patrol Stations within the Del Rio, Texas, Sector. Follow him on Twitter @RandyClarkBBTX.