They might find them in the ruins.
Be sensitive, please.....
Two questions immediately come to mind.
1. Do the Russians even have a proper anti-terrorist force, like the SAS, Delta, or Seal Team Six that can handle a building assault?
2. Why couldn't they secure a proper perimeter around the school that would ensure NO ONE would get away? Hell, even my county's 18 member sheriff's office knows how to manage that?