Exclusive: Behind the scenes at the NYPD Counterterrorism Bureau

NEW YORK (WABC) -- Roll call at the NYPD Counterterrorism Bureau can be an earful, but when they roll out, heavily armed, and fan out across the city, they know precisely the kind of threat they might face.

When terrorists strike anywhere around the world, a team of NYPD analysts get to work to learn as much as they can about the attack.

"Getting the New York question answered," Chief James Waters said. "What does it mean to New York, to New York City, in protecting New York?"

They share what they learn with Waters in an office with maps of the world and real-time monitors of local New York hot spots. TV cameras have never been allowed in the meeting before, and some of what is discussed is classified. But the idea is always the same.

"What makes me worry is what I don't know," Waters said. "The piece of information, the piece of intelligence that either hasn't surfaced or that you just don't know yet."

Consider just the possibility of a dirty bomb. Police on the street carry radiation monitors that would detect a dirty bomb within several feet, and some have a device that can scan larger areas. Additionally, the NYPD can scan ships for radiation before they even enter New York Harbor.

"I grew up in New York, most of my friends and family, for the most part, live on the island of Manhattan or the surrounding boroughs," analyst Morgan Hitzig said. "And if I can do what I can to protect my friends and family, I'm going to do that first and foremost."

Much of the work to protect the city from a nuclear or radiological device happens within the secret location, which has never been on camera before now.

"We're as prepared or better prepared than any other city in the country," Dr. Andrew Karam said. "And probably better than any other city in the world."

Still, the threat is daunting. And knowing it so well can be consuming.

"I wish I could walk out the door and forget it, because sometimes it's very heavy information," another analyst said. "But you think about it every second of the day."