KANSAS CITY, Mo. — Gabe Wallace, his left temple bloodied, wrapped his arms around a friend he’d lost track of amid the deadly gunfire. The two Shawnee Mission East sophomores had attended the Chiefs’ rally at Union Station to celebrate a Super Bowl. Instead, they buried their heads on each other’s shoulders, tears flowing down their faces. They were both safe. “I love you, man,” Wallace said. “I love you.” Gabe and his friend Hank Hunter were with others outside Union Station when, after the celebration ended, shots were fired. Soon, they would be frantic and separated from each other, unsure…