Transcript for Migrant tragedy
NARRATOR: Last night, a vigil in San Antonio for the victims of the deadliest human smuggling case in US history, 51 lives lost.
- I'm so fed up. I'm so tired.
NARRATOR: For Jessica Azua, this tragedy hits close to home.
- I came here when I was 14 years old in an 18 Wheeler as well. And I passed out from the heat. I was lucky that I woke up.
NARRATOR: Officials say at least 62 migrants were stuffed into the back of this tractor trailer abandoned Monday in the Texas heat. Temperatures topping 100 degrees. By the time first responders arrived, most of the men, women, and children were already dead. The
- The floor of the trailer was covered with dead bodies.
- The survivors rushed to the hospital, some in critical condition. San Antonio's Archbishop visited them in their beds, the only one with the strength to speak was a 16-year-old girl.
- They were all with tubes. They couldn't talk at all.
NARRATOR: At least three people have been taken into custody, including the truck driver. Investigators tracing the truck's registration to a home in San Antonio and detaining two men from Mexico on weapons charges. Human smuggling a growing problem now because of the record surge of migrants arriving at the border from Central America and Mexico. 239,000 were detained last month alone.
- The lead investigator on this case telling me that he is increasingly concerned for the fate of migrants with migration increasing along the Southwest border because smugglers are putting more people into increasingly hazardous vehicles.
NARRATOR: Border patrol officials now with this warning to people desperate to cross into the US.
- With the rising temperatures in South Texas, this is a guaranteed death sentence. It's not worth it. Do not place your life or the lives of your loved ones in the hands of these criminals.
- The local Sheriff is asking President Biden for more resources to fight human smuggling, calling it a humanitarian crisis. The Sheriff also blamed the governor for what he calls ineffective tactics at the border.
This transcript has been automatically generated and may not be 100% accurate.