Pfc. Marquest Smith, a former Fort Worth resident who joined the Army just over a year ago, was in a small cubicle inside the Soldier Readiness Center when he heard popping sounds. A bullet tore through the cubicle wall and lodged in the heel of his boot. Within 15 minutes, the 21-year-old soldier was rushing through the chaos in the huge processing center to pull four wounded victims to safety and help take them to the hospital. The gunman fired toward him from across the room as Smith was fleeing the building. Other tales of heroism spread throughout this grief-stricken...