What if: Shoot her!
O.K., I'm being facetious. But the shooter said he was only going to shoot one - so what if both girls had said 'shoot her'?
And another thing, I think this movie is kind of sexist in the way it has the girls just passively standing there like lambs waiting for the slaughter. And they were both bigger than the little twerp!
When he changed clips, they should have lept on him! Geesh!