I only shot two of the police officers who happened to be among the civilians, other than that i didn't fire at a single person until the special forces arrived. I have to say, although i was kinda prepared through the media / forum discussions i still had a queasy (i hope thats the right word) feeling walking through the halls.
In retrospective i don't think that scene is much worse than what can be seen in some oppressive movie scenes. It didn't do much good on the video game controversy since it undermines two of the arguments against the critics: that shooting of civilians isn't possible or at least encouraged, and that scenes in video games do not resemble those in actual amok runs (and therefore cannot be the blueprint for them).
The german version of the game ends when you shoot a civilian in that scene. It doesn't make much sense, but it's one of the rare cases where i could live with (that kind of) censorship; although i bought the UK import nonetheless.