The U.S. federal prison system was placed on lockdown nationwide following a deadly incident at a Texas prison, officials said Monday. “Multiple inmates were observed fighting at the United States Penitentiary Beaumont” in Texas, said the Federal Bureau of Prisons in a news release. Prison staff then “immediately secured the area” but found inmate Guillermo Riojas and inmate Andrew Pineda with life-threatening injuries, prison officials said. They were transported to a nearby hospital, where they were both pronounced dead, the bureau said. Meanwhile, it added, “Two additional inmates were transported to a local hospital for further medical assessment and treatment.”...