There would not have been more dead kids,
Says you? How do you know that someone else having a gun during the ordeal would not have provoked the gunner further and made him more aggressive? Or that the addition of the other gun causes someone to get hit by an added bullet fire (cause even the most trained people can make mistakes under pressure)? If we are going to play the what if game with the added guns, why ignore the negative possibilities (other than, it makes your point of view seem better).