Laws of land warfare state, one can fire on the enemy while enemy escapes.
If Marines in Iraq take a prisoner to investigate, (like kicking in a door of a home), and hold them in the home until identification can be verified, prisoners may try to escape.
So Dad runs, Marines fire, then Family runs becuase Dad shot, and Marines may or may not fire. They already determined who to shoot if they ran. War is complicated, but Marines are human beings and professionals, and will just NOT shoot anyone.
I thought I would mention this because as a writer, I get a lot of harrassments at book signings by people who do not understand the laws of land warfare set by the Geneva Convention of 1949. Even when you battle a country who does not enforce the Geneva Convention like we do. Many fellow American's don't understand just how professional and caring our troops are, compared to most of the world.
I have had a few ugly scenes at book signings where individuals (never alone) start a loud showing of their opinion of the war, and try to get me to argue with them. I always tell them I will be happy to debate with them after the signing, until then, FUCK OFF!