Arterial bleeding can kill in a matter of minutes. Broken bones make it very difficult to fight back. And, a well-aimed stab or slash could kill you almost instantly.
The kids would be too terrified to fight back in any meaningful way. The adults would try, but without a weapon of their own they would have to either improvise one or use their bare hands--and the latter option would be borderline-suicidal. They would also be acting on reflexes and adrenaline, which means that unless they've had combat training they would probably be ineffective fighters.
Even if they rushed him, they would be unable to grab his sword without getting their hand cut off. They would also lack a way to quickly take him down, unless they found something like a hammer or a baseball bat, and that would require them to get close to him--which would likely be fatal unless they killed or incapacitated him in one hit. And all that adrenaline would cause them to think very, very fast, making a miss quite likely.
Admittedly, they would have slightly better chances. But not much better, and it's certainly not impossible that he could have done the same thing.