In case of emergency, is it teacher's responsibility to help the student evacuate or protect students?

I believe in the case of public schools (el, mid, and high) the teacher is obligated to stay with the students and direct them where to go and what to do. In our school we have drills often so that in case of emergency the teacher doesn't freak out and leave the students alone. Same thing with the firearms. In that case, the teacher should immediately bring in any students from the hall, close and lock the door, direct students to their specific place and perhaps call the office to report what is happening. It differs from school district to school district. In every case the teacher should remain with the students. I think any teacher who bolted would be fired.