Unfortunately, I have just gotten a firsthand look at this, as there was a (nationally publicized, I believe) shooting at the college just down the street from me yesterday. Two or three dead and two or three injured - the shooter was an instructor who had been denied tenure and she shot several of her colleagues. We had a choir concert scheduled for last night with a community group, but our director also teaches at the college and several of the choir members are students there. The whole campus was a madhouse, and in fact nobody even bothered to let their building's chair know they were out of "lockdown" until another faculty member saw it mentioned on the news and called in to the head of the department. The victims' names were released on Twitter before the police said anything official. I think it's really unfortunate that it happens that way, but it's just the nature of how we pass and process information nowadays.
(None of the people associated with our choir were involved in the incident, although a few had taken classes from the shooter and the injured faculty. Really, as an "outsider" in that kind of situation, what do you do?)
One thing a lot of people don't realize is that trauma survivors don't need anyone to "do" anything for them, other than listen. It's hard to listen to some of what they're saying, but that's probably the best thing for them. And they may want diversion. I would just reach out to them and let them know you are there for them