Mayor Michael Bloomberg says the terrorism arrest is a reminder that New York City can’t let its guard down.

Bloomberg also says “freedom is fragile” and it’s important to remember the lessons learned from 9/11.

A 21-year-old man is being held without bail after being charged with plotting to blow up the Federal Reserve building in Manhattan.

Quazi Nafis was arrested Wednesday after a sting operation. Authorities allege he parked a van filled with what he believed were explosives outside the building and tried to detonate it.

Bloomberg made the comments Thursday at an unrelated event.

(AP)