Would you be able to hurt someone in order to try and save their life?

I was watching a tv show about the Beslan hostage crisis in Sept. ‘04. They described an incident where a little girl somehow got outside the building and was sitting on the front lawn looking confused. She stood up and was trying to climb through the window to get back inside the gymnasium where the hostages were. A russian sniper was requesting permission to shoot the girl in the leg to stop her from going back inside. What a horrible amount of guilt one would have to live with doing something like that, would you be able to do it?