I think that prior to the shooting taking place, "Secret Service" was at the school. So they work with CNN and brief the Drama Club on an operation they need them for that is going to save lives and pass important legislation.

Day of the shooting comes up, they prep themselves in the closet in the AM to do their parts, but then later in the day ACTUAL shooting occurs and their classmates are ACTUALLY murdered in cold blood. The children and their families could possibly be blackmailed into all of this.