We have to avoid the knee jerk reaction to random crimes like this. The American way is to escalate force. Mass stabbings? We need more guns. Mass shootings? Even more guns..... etc.
We should reject and avoid this. You simply cannot save everyone from a random attack.
The only way to address it is for more surveillance of citizens. But when it comes to, say, digital ID's, there is a sizable number of people saying it's government going too far. You simply cannot have it both ways.
It's a reality of life. Mass killings will happen if someone is determined. Of course it's wrong, but it's a mistake to imagine they can all be avoided.