NYPD conducts dirty bomb'drill on the Third Avenue bridge. (April...

NYPD conducts dirty bomb'drill on the Third Avenue bridge. (April 5, 2011) Credit: AP

They are coming by land, air and sea.

Tuesday, scores of NYPD officers, as well as cops in New Jersey and Connecticut, fanned out across the metropolitan area in a mock hunt for one New York's most dreaded scenarios -- a dirty bomb attack.

The five-day exercise, part of the federal Securing the Cities Initiative, is aimed at honing the skills of police at interdicting radiological devices -- crude explosives that terrorists could use to spread radioactive contaminates around the city.

Coordinated by the NYPD, the exercise, which ends Saturday, involves four cells of a fictional terrorist group that wants to target New York City with a dirty bomb. The "terrorists" are actually law enforcement officials transporting low-level radioactive substances.

"Over 400 check points will be manned by law enforcement throughout the metropolitan area," police Commissioner Ray Kelly said as the first NYPD teams assembled near the United Nations building Tuesday morning. Police units were posted at bridges coming into Manhattan like the one at 138th Street. Police and U.S. Coast Guard units will also be patrolling harbor waters.

By late Tuesday, police officers using radiation detectors had found all 17 radiation sources in the exercise, as well as four real-life sources linked to radiation medical treatment that weren't part of the drill, said an NYPD spokesman.

"It's an attempt to push protection out from the city," said Inspector Stuart Cameron of the Suffolk County Police Department, which will be patrolling Long Island highways and waterways Thursday and Saturday. Suffolk helicopters will also be used, Cameron said.

Federal officials are also running exercises for area police and hospital security staffers at the Y-12 National Security Complex in Oak Ridge, Tenn. A daylong exercise was witnessed in November by a Newsday reporter on the condition that no participants be identified. Mock terrorists tried attacking a hospital where radioactive sources were stored. Officers then had to counterattack.

Deidre, of Garden City, who once worked at police headquarters in Manhattan before retiring and taking a security job, said the November training was the best she'd ever had. "I thought it was realistic, I thought they had some excellent instructors," she said. "I am glad that I went."Cameron said Suffolk plans to send officers to the Oak Ridge training this year. Nassau is considering it.

Latest video