The school with the locks have a liability. The police in this case might have a liability. They physically prevented an officer who was active shooter trained from entering and possibly saving his wife .Some one prevented the Border patrol team from going in earlier. There might be a legal difference in the doctrine that while the police don’t have a responsibility but they might have legal liability for their overt actions. Something the court might consider.And the SCOTUS has already ruled that the police have no responsibility to individuals.