You have to imagine what was going on in the heads of everyone inside. They probably had limited information about how many people were outside trying to get in. How would any of us feel trapped in a building with a raging mob busting in the windows and doors? How would anyone feel hearing and seeing this raging mob getting past the heavily armed security of that building? They had no way of knowing if it was just a couple of knuckleheads with a flag or a massive force of heavily armed men.