Lots of good advice here for you to follow. I add my wishes of you and your community being able to accept and mourn what has happened and eventually move on.
My mother committed suicide when I was 21, and her psychiatrist contacted me to make sure I knew I wasn't to blame, nor could I have done anything to have stopped her. I was aware of both these things, but only because I had lived with my mother's depression all of my life, and had even discussed her suicidal feelings with her. In a way, I was well-prepared when what happened happened, though there is not a day that goes by when I don't wish she hadn't made that decision.
Survivor guilt is what we are left with...that and a great surge of our own survival instinct. This is probably the strongest instinct we possess, so one can imagine the psychic pain of someone who fights and wins against it. All the more horrific when it is a child involved.
The lessons are myriad, but early warnings can often be seen by friends, teachers and family members. To err on the side of caution and make sure the children (and all members) of your community are both listened to and respected will help bring you closer together. Help and support need to be on offer, but if such a tragedy still befalls you, at least you all will know every effort was made to help.