DONNA, Texas — The dirt roads in the Lower Rio Grande Valley National Wildlife Refuge curve just beside the river as brush folds over the dry cracked dirt as far as the eye can see.

It makes every road look exactly the same, which is partly why Fabiola Peña and her two sons had been walking in circles, for hours.

The mother hadn't realized they’d entered the U.S. until Border Patrol agents found them along with six other Guatemalans who had just crossed the border.

“My son, we’re in the United States,” Peña told her eldest son in Spanish. Crying, the two were overcome with joy as she told her sons they wouldn’t have to go back to their country.

Border Agent Hermann Rivera didn't have time to stop for Peña and the others. He gave them water bottles, made sure they didn’t have any pressing health issues and told them to head west on a different dirt trail, so they wouldn’t get lost again.

Then it was back in the car for Rivera, on to the next group of families.

A Border Patrol station toured by NBC News was supposed to have a capacity for about 380 migrants who had crossed the border, but instead had more than 1,200.

Two new camps

On Thursday, federal authorities opened two large “soft-sided facilities” — essentially tent cities — one in El Paso and the other in Donna, near McAllen.

Groups of families and unaccompanied children are crossing the border in the Rio Grande Valley by the hundreds per day. Agents say the flood of people is "nonstop," and report 1200 to 1500 apprehensions per day - making it the busiest area of a border for the entire country. Annie Rose Ramos

John Morris, acting deputy chief patrol agent in the Border Patrol’s Rio Grande Valley sector, called them a “Band-Aid” to help deal with the dramatic overcapacity at other federal facilities.

“The processing center in McAllen is full,” said Morris. He said the McAllen Border Patrol station is full too. “I’ve got 1,200 people in a facility meant for 384.”

At this stretch of the border alone, Morris said they see anywhere from 1,200 to 1,500 migrants a day.

Morris said his sector is “overwhelmed” in responding to the largest influx of migrants in more than a decade. They're mostly families and unaccompanied minors, and they don't run away from Border Patrol agents. In fact, they are looking for them.

“The smuggler will tell them to walk up and follow that road until you see a green and white vehicle, an agent dressed in green, and tell them you’re there to turn themselves in,” Morris said.

Each of the two tents opening up in El Paso and Donna can fit up to 500 migrants, mostly families or unaccompanied children, for no more than 72 hours. From there, adults and their children will be turned over to Immigration and Customs Enforcement, and unaccompanied children will be taken by the Office of Refugee Resettlement.

NBC News toured the new facility in Donna, which was broken up into four 8,000-square-foot air-conditioned pods. Each pod will hold up to 125 people who will sleep on mats and will have plastic dividers to offer some privacy. There are small guard towers that will be staffed by security personnel.

Inside the Border Patrol station, 700 migrants stood in a concrete “sally port” — essentially a garage — outside of the station building because there wasn’t any more room inside. People were separated into two large groups by steel chain-link fencing.

Inside the station, in between the holding cells, diapers were stacked on tables against the wall. Baby formula and bottles sat next to water jugs. Mothers stood in line, holding their babies, waiting for baby wipes.

Morris said smugglers are telling Central American migrants that if they arrive with a child, they won’t be separated and will be allowed to stay in the U.S.

“This is a border security crisis and a policy crisis,” Morris said. “The child is now known as the ticket. If you cross with a child you will only get held for 20 days, which of course the smugglers will exploit, so we’re seeing children that are being recycled.”

Deadly reminder

On Wednesday, a raft carrying nine people capsized on the Rio Grande, according to Customs and Border Patrol. A 10-month-old was found dead and three other people — described as two boys, ages 6 and 7, and a man, were missing.

Border Patrol agents began a search-and-rescue mission after a man who was apprehended for crossing the border illegally told them his wife and two children were missing in the river after their raft capsized.

Agents found the man’s wife and eldest son, a six-year-old boy, crying for help from the river, struggling to stay afloat but alive. Agents then found the man’s 10-month-old son several miles downriver, deceased.

The incident is another reminder of the high stakes for migrants at the border.

"What we're dealing with now is senseless tragedy," said Raul L. Ortiz, chief patrol agent of the Customs and Border Protection's Del Rio sector.

Nonstop

Kenny, 19, who doesn't want to use her full name, searched out Border Patrol Agents to help her with her 1-year-old daughter, Jacel Michele.

One-year-old, Jacel Michele, and her mother, Kenny, were found by Border Patrol agents after walking for hours along the dirt roads. They were lost and Kenny was worried her daughter's fever was getting worse in the heat. She poured the water agents gave to her over Jacel Michele to keep her fever down. Annie Rose Ramos

The toddler had been fighting a fever in the past few weeks since they had been traveling from Honduras to get to the United States.

“Her fever gets worse at night,” she said. They had walked on the snaking dirt roads in the refuge for hours, and Kenny could feel her daughter’s fever getting worse.

When Agent Rivera found the mother, he gave her water that she quickly poured over Jacel Michele’s head.

The toddler laughed as water poured down her green shirt that read "Virgen de Suyapa" – for "Our Lady of Suyapa," the patron saint of Honduras.

Holding Jacel Michele and a plastic bag filled with diapers, Kenny said she had no other choice but to leave her home country where there aren’t any jobs to support her and her daughter.

Again, Rivera couldn’t stay. He’d gotten word another group of migrant “family units,” were wandering around on the dirt roads, in over 90-degree heat.

The Rio Grande Valley sector is the busiest place in the country for families and unaccompanied children apprehensions, according to CBP.

Rivera told Kenny’s group to wait under the shade and that he’d call for other officers to come and pick them up in vans.

“It’s like this all day long,” he said. “Nonstop.”