Mexican authorities prevented the smuggling of 150 migrants crammed into a large truck over the southern border amid dangerously temperatures in Texas, Fox News has learned. 

Law enforcement in Mexico were assisted by agents with the U.S. Customs and Border Protection's Del Rio Sector, which covers 245 miles along the Rio Grande and Lake Amistad along the border, when they stopped the truck. 

All the migrants survived. Images of them in the 18-wheeler truck show many sitting in cramped spaces in the summer heat. 

The attempt came weeks after 53 migrants were found dead inside an abandoned commercial truck in San Antonio. The dead included a 13-year-old and 14-year-old from Guatemala and two 16-year-olds from Mexico, authorities said. 

MIGRANT ENCOUNTERS AT SOUTHERN BORDER EXCEED 2 MILLION SO FAR IN FY 22, AS BIDEN-ERA CRISIS CONTINUES

Migrants at the U.S.-Mexico border

A truck carrying 150 migrants was stopped along the U.S.-Mexico border, Fox News has learned. (CBP)

Four people have been arrested in connection with the June 27 discovery, including the driver. 

Migrant encounters at the U.S.-Mexico border have so far exceeded 2 million in fiscal year 2022, sources told Fox News. The CBP announced Monday that there were 199,976 migrant encounters in July, taking the total so far this fiscal year to 1.946 million encounters.

The rising numbers coincide with widespread criticism of the Biden administration from officials in border states. In response to what they see as a lackluster response from the federal government, Texas and Arizona have recently started moving migrants to Washington, D.C., and New York City in protest. 

san antonio semi truck where dead migrants found inside

In this aerial view, members of law enforcement investigate a tractor trailer on June 27, 2022, in San Antonio, Texas. According to reports, at least 46 people, who are believed migrant workers from Mexico, were found dead in an abandoned tractor trailer. Over a dozen victims were found alive, suffering from heat stroke and taken to local hospitals. (Jordan Vonderhaar/Getty Images)

CLICK HERE TO GET THE FOX NEWS APP

Many Republicans blame the rollback of Trump-era policies, which slowed the flow of migrants into the U.S. 

Fox News' Adam Shaw and Griff Jenkins contributed to this report.