At least 50 migrants have died and several others were taken to local hospitals after being inside an overheated truck-trailer in San Antonio, Texas, officials say.

Among the dead, 22 were Mexican nationals, seven were from Guatemala, and two were from Honduras, says Mexican President Andrés Manuel Lopez Obrador.

Authorities are working to identify everyone who was inside the abandoned trailer.

Three people are now in custody but police don’t know how connected to the trailer they are, said San Antonio Police Chief William McManus.

On Monday, authorities arrived to the scene after someone who works in the area the truck was found, heard cries for help and saw at least one body, NBC News reports.

Police say the migrants were suffering from heat stroke and heat exhaustion.

Temperatures reached 101 degrees Fahrenheit on Monday, according to the National Weather Service.

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