you telling me this classroom had no windows? Assault through windows and door at the same time - use some basic tactics and guts - overwhelm the bastard. Once you have more than 2 armed responders, any delay in going right after the bastard is more cowardice and/or a complete failure to understand the situation.
Like many Southern schools, it's got as much glass area as solid wall.
Did they bother using binoculars from a distance all around the school to see if they could find which classroom he was in? Or did they just hang out in the parking lot?