A building has no preference about who does or does not go into it. Even though I was not there, I can almost guarantee that God heard from plenty of students and teachers who have been in harms way during the spate of school shootings going on over the last few years.
God was also present and working through the actions of the heroes who saved others lives at the expense of their own.
God goes where people go. The building that the people are in is unimportant.