Stealing from Weer'd's playbook, we had an unpossible occurence in the gun-free utopia of the Chinese People's Republic.
28 dead and 113 injured by a mass knife attack at a train station.
So even if it were only the 5 suspects killed, that's over 5 dead and 22 injured by each one. (Edit: Some news agencies are reporting 10+ assailants)
So I don't believe this actually happened since we've been told over and over there could never be a mass killing w/ a knife.