The six migrants who died after Mexican soldiers fired on the pick-up truck they were traveling in were from Egypt, El Salvador and Peru, Mexican President Claudia Sheinbaum said on Thursday. The killings, which occurred in the southern Mexican state of Chiapas on Tuesday, underscore the tensions on Mexico’s southern border as it faces U.S. pressure to contain migration. “It’s a regrettable event and it must be investigated and punished,” Sheinbaum said, speaking in her regular morning press conference. She said the attorney general’s office was investigating the incident. “A situation like th…