US opens probe after 51 migrants die in sweltering trailer

The death toll of undocumented migrants who were abandoned in a scorching-hot trailer in Texas rose to 51 Tuesday, as President Joe Biden blamed "criminal" professional smugglers for the tragedy.

Rebeca Clay-Flores, a Bexar County official, reported the new tally of "39 men and 12 women" dead, following the Monday discovery of the tractor-trailer on an isolated road in her district.

She did not say how many survivors remained in hospital, but the number could be around 11 based on initial figures that officials gave, including possibly four children.

The Department of Homeland Security announced it had opened a criminal investigation, as Biden took aim at human smuggling gangs.

"The tragic loss of life in San Antonio, Texas that took place yesterday is horrifying and heartbreaking," he said in a statement.

"This incident underscores the need to go after the multi-billion dollar criminal smuggling industry preying on migrants and leading to far too many innocent deaths," he said.

Federal law enforcement agents on Tuesday arrested two men at the address linked to the tractor-trailer's registration, court documents showed.

Juan Francisco D'Luna-Bilbao and Juan Claudio D'Luna-Mendez, both Mexican nationals whose US tourist visas had expired, were illegally in possession of multiple firearms, the documents alleged.

A third person, suspected of being the driver of the tractor-trailer, was arrested nearby while "very high on meth," reported the local daily San Antonio Express-News, citing a law enforcement officer.

According to Mexican President Andres Manuel Lopez Obrador, of the dead whose identities are known, 22 were from Mexico, seven from Guatemala and two from Honduras.

"It's a tremendous...