Texas authorities found 29 illegal immigrants aboard railcars over the weekend, days after three others were found dead in similar circumstances along the southern border. 

The Texas Department of Public Safety said troopers found the migrants Sunday inside a railcar in Maverick County. They were all handed over to the U.S. Border Patrol, the agency said. 

That same weekend, a Mexican migrant died after being trapped in a shipping container at a Union Pacific train yard in Eagle Pass. The incident is suspected to be related to human smuggling, sources said. 

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Officials for Union Pacific Railroad later said that 15 people were found in the rail car, two people died while four were air-lifted to San Antonio, and six were taken to nearby hospitals.

Authorities responded and found 12 migrants from Mexico, Ecuador, Honduras, and Colombia, Texas Public Radio reported. One of them was dead. 

On Friday, 17 migrants were found suffocating in another train car where two Honduran men were found dead inside. 

Homeland Security Secretary Alejandro Mayorkas said in a statement that the agency is "heartbroken to learn of yet another tragic incident of migrants taking the dangerous journey."

"I thank the Border Patrol Agents who responded to the scene and the HSI Agents who are supporting the investigation in Uvalde. We will work with the Uvalde County Sheriff’s Office to hold those responsible. Smugglers are callous and only care about making a profit," he said.