The caller said the student had a gun. Placed on the night of May 1 to Colgate University’s campus safety department, the call provoked a full-scale lockdown of the upstate New York college. For four hours, students waited in their dorms as police combed the campus for the shooter. Soon, though, it became clear that the caller had been wrong. There was no active shooter. Instead, the caller had seen a black student walking into an academic building holding a glue gun.