At least 8 people injured by knife-wielding attacker in ISIS-linked mass stabbing
The only effective defense to asymmetrical terror is asymmetrical defense like individual concealed carry, which is what saved the day here. The individual was not an on duty police officer. He was off duty, but carrying concealed. It is impossible to provide sufficient security to avoid encounters like this by determined terrorists. However, eliminating "gun free zones" which only provide terrorist, and criminals with a secure hunting ground, and simplifying, and encouraging concealed carry can stop violent acts in their tracts.
This is a simple easy to use primer. Do we want more acts of terror? If so, we need more gun free zones, and less concealed carry, if not, then we need fewer gun free zones, and more concealed carry.