Laredo Sector Border Patrol agents found a group of 53 migrants locked in the back of a tractor-trailer after it entered an immigration checkpoint near the Texas border. Officials said the temperature inside the locked trailer exceeded 100 degrees.

Laredo North Station Border Patrol agents assigned to the Interstate 35 Immigration Checkpoint observed a tractor-trailer approaching for inspection in the northbound lane. During the initial interview with the driver, a K-9 agent alerted to an odor it is trained to detect. The agent referred the driver to a secondary inspection station for investigation, according to information obtained from Laredo Sector Border Patrol officials.

Agents conducted an investigation and opened the rear of the trailer. During the inspection, agents found 53 migrants from Ecuador, El Salvador, Guatemala, Honduras, and Mexico, officials stated.

The agents observed the temperature inside the trailer at the time of the inspection to be 105 degrees. The agents followed up with a medical evaluation of all 53 illegal aliens and determined that non required medical attention despite the heat.

Officials seized the tractor-trailer rig and placed the driver, a U.S. citizen, under arrest for allegations of human smuggling. All were turned over to U.S. Immigration and Customs Enforcement’s Homeland Security Investigations agents for further investigation.

So far this fiscal year, Border Patrol agents rescued more than 3,000 illegal aliens from life-threatening situations during human smuggling attempts like the one described above, according to Border Patrol Chief Carla Provost.

“The harsh conditions smugglers expose them to often lead to severe injury or death. Tragically, too many have died while being smuggled,” the chief Border Patrol agent tweeted earlier this week.

Last week, Breitbart Texas reported on about 26 migrants being rescued during dangerous human smuggling operations. In one case, a migrant was found locked in the toolbox of a pickup truck with no means of escape.

“Many lives have been lost in horrible conditions caused by smugglers locking immigrants in toolboxes, car trunks, and tractor-trailers,” Del Rio Sector Patrol Agent in Charge Raul L. Ortiz said in a written statement. “With temperatures over 100 degrees and no way to escape, this could have ended tragically.”

Border Patrol agents also frequently put their own lives in danger in order to rescue migrants from life-threatening conditions.