You are still more likely to be hit by lightning on a college campus than be shot and killed by a random gunman.
But nobody calls for a lockdown every time thunderstorms are predicted.
And I bet you are more likely to be in an earthquake in Japan than be shot on a college campus in America.
Re the Israeli professor who gave his life to save his students..it should also remind us that Israelis face this threat EVERY day, and have done so for decades...
Mass shootings on the other hand, are something we Americans did not have much of until the last thirty years or so, and are purely human acts, statements of evil born out of the sick, depraved, lack-of-respect-for-human-life society we must all somehow live in.