2 migrants who died in a sweltering Texas truck were 'excited' to travel to the US so they could finally build their mom a house, their devastated mother said

• Two migrants who died in the Texas truck tragedy were so "excited" to make the journey to the US.
• They wanted to build a better life and their mom a home, their mother Karen Caballero told Noticias Telemundo.

Two Honduran migrants who died in the Texas tractor-trailer smuggling tragedy were so "excited" to make the journey to the United States to build a better life — and build their mom a home — their devastated mother said.

"They were excited to do the trip. Every day, they would ask me, 'Mom, when are we going to leave?' " Karen Caballero told Noticias Telemundo about her sons Fernando Redondo Caballero, 18, and Alejandro Miguel Andino Caballero, 23.

"It seemed like they were going to a birthday party, like when they were little and would ask me 'Mom, when is the birthday party?'" a tearful Caballero said.

Her son, Alejandro, couldn't wait to get to the US so that he could work and save up money so that he and his brother could purchase a home for their mother.

"Alejandro was excited that he already wanted to be there," said Caballero. "He said he was going to work. It made me laugh when he told me, 'Mom, when we're there, we'll finally build your house.' And I told them, 'I won't want that house because you will no longer be here.'"

Caballero's sons were among the 53 migrants who died after they were apparently left in a scorching hot big rig that was abandoned and discovered by authorities in a remote area of San Antonio, Texas, on Monday.

Temperatures soared into the triple-digits that day and a fire official said that the survivors were "hot to the touch" and "suffering from heat stroke, heat exhaustion."

Sixteen people found in the back of the tractor-trailer were hospitalized in the aftermath; five of them later died.

The tragedy has been described by authorities as the deadliest human smuggling incident in modern US history.

Before Fernando and Alejandro embarked on the journey north from their hometown in Honduras, Caballero said she told her sons, "Make life on your own — triumph, focus."

"And yes, the hugs, the kisses, the affection," Caballero recalled. "Alejandro is like a loving bear. He's huge, my son is. Huge. He's beautiful — both of my sons are."

Caballero told the Associated Press that 24-year-old Margie Tamara Paz Grajeda, who lived with Alejandro, also joined the sons on the journey to the US.

"We all planned it as a family so they could have a different life, so they could achieve goals, dreams," Caballero said.

The mother explained that she believed "things were going to go well," but that Alejandro was more cautious.

"Who was a little afraid was Alejandro Miguel. He said, 'Mom, if something happens to us...' And I told him, 'Nothing is going to happen, nothing is going to happen. You are not the first nor will you be the last human being to travel to the United States.' "

The chief of Mexico's National Immigration Institute said that 27 people from Mexico, 14 from Honduras, seven from Guatemala and two from El Salvador were among the dead, according to the AP.

Four men have been federally charged in connection to the incident, including 45-year-old Homero Zamorano Jr., who was charged with one count of alien smuggling resulting in death.