The gym was silent except for the occasional whisper while everyone waited to hear what the situation was. It was standard protocol for the students to be brought in to one of the designated safe buildings in the case of an emergency. The gyms were the safe spots set up with sealing devices and hidden food stores.
On top of all of this, there were separate internet connections that only the staff knew how to work. This was made in case the school was attacked or if the school was hacked in to. With the development of super powers around the world, many super power holders were found to have destruction capabilities. It was only natural for the world to adapt to this.
There were people that could cause tidal waves when they sued their super powers and accidentally flood a coastline. There were people that could accidentally set city blocks on fire. There were even people who could zap all electronics in to a fried melted hunk on the floor.