San Antonio (AFP) – US authorities opened a criminal investigation Tuesday after 50 migrants packed into a stifling trailer died in Texas, with President Joe Biden blaming professional smugglers for the tragedy. A spokesperson for US Immigration and Customs Enforcement said the toll had risen overnight after the tractor-trailer rig was discovered Monday abandoned on an isolated road near the city of San Antonio. Sixteen people, including four children, were taken to hospital suffering from extreme dehydration. Most of the fatalities were Mexican, and US media said some victims died in hospital…