Like in Gringotts, the Aurors fell very fast. Being all purebloods, none of them understood the inherent danger of firearms until it was too late. Some managed to cast a shield to protect themselves. The others, who tried to go on the offensive, did not manage to cast in time before getting shot. Unwilling to defend a goblin bank, the surviving Aurors decided to run away until they joined their colleagues in the grave. Diagon Alley was soon empty again.