HOUSTON - Over the last 16 years, according to U.S. government records, more than 6,000 people have died after crossing the U.S. border illegally from Mexico and finding themselves in a dangerous environment. Yet illegal immigrants, mostly from Central America, continue to cross the border in south Texas, where temperatures are soaring.

In south Texas, the Rio Grande river that marks the border with Mexico is fairly easy to cross.

But once across, the undocumented immigrants find little water, heavy brush and many small creatures with nasty bites.

U.S. Border Patrol agent Jason Owens said smugglers often leave people on their own here.

"The guides that bring them across, if they can't keep up, they leave them behind; they walk around lost… no water, no idea where they are supposed to go, no form of communication. This close to the river a lot of people can find themselves in trouble and die," said Owens.

Owens said the human smugglers are part of a Mexican criminal world that includes drug trafficking cartels responsible for killing thousands of people.

"Among the smuggling groups you see infighting with the cartels, the cartel fighting with the Mexican authorities, who are doing their best over there to get control of the situation and then they come over here and a lot of time you have the same thing," continued Owens.

Hundreds of unidentified bodies have been discovered in south Texas. Many of them were dug out of the ground by a volunteer forensic team from Baylor University.

Those who come from Central America are fleeing drug gang violence and poverty in countries like Honduras.

On the long journey through Mexico, many are robbed and abused, including children who travel alone.

Border Patrol spokesman Peter Bidegain said that once they cross, the child immigrants often seek the protection of the agents and confide in them.

"A lot of times when you ask them about their journey, they start to cry.  It is very emotional; it is emotional for the agents, it's emotional for the kids," said Bidegain.

Tony Payan, who heads the Mexico Center at Rice University's Baker Institute, said child smugglers face little danger of being caught.

"What these guys do is take the child to the US/Mexico border and then they push them across the river without having to cross themselves, so they are not exposing themselves to being arrested and detained," said Payan.

As long as many people are able to make it across the border and stay, experts say people in Central America will continue to pay smugglers thousands of dollars per person.

Despite the dangers, Payan said what many immigrants face at home is worse.

"Enormous, very deep poverty in Central America, and hopelessness and when people are hopeless they are going to move.  It has been the history of mankind," said Payan.

In Texas, Border Patrol agents continue to lookout for drug smugglers and for those who cross the border illegally and risk their lives in a harsh environment.