A new program aimed at keeping Americans safe from terror attacks will rely on individual citizens to serve as "the eyes and ears" of their communities.

Police chiefs cited the case of Najibullah Zazi, seen here in New York City on Sept. 25, when endorsing the iWatch program. (AP photo)

iWatch is a community watch program endorsed by police chiefs across the U.S. that teaches people how to detect suspicious behavior and report it to police.

"We can and must work together to prevent terrorist attacks," reads an announcement from the Los Angeles Police Department on the iWatch Web site.

L.A. Police Chief William Bratton, who developed the program with Police Commander Joan McNamara, called it the 21st century version of Neighborhood Watch, a program that encourages local residents to stay alert and informed about their neighborhoods.

"A single observation, a single report can lead to actions that can stop a terrorist attack," warns a Public Safety Announcement video released by the LAPD.

When the chiefs of the 63 largest police departments in the U.S. and Canada met to endorse iWatch at a conference last Saturday, they cited the case of Najibullah Zazi - the Denver man suspected of having ties to Al Qaeda who has been accused of plotting to use a weapon of mass destruction within the U.S.

Federal authorities say Zazi, 24, sought to build a powerful bomb with ingredients he purchased from beauty supplies outlets at Denver-area stores.

When an inquisitive clerk asked why Zazi was purchasing such large amounts of cosmetic chemicals, Zazi is said to have answered that he had "lots of girlfriends."

The clerk's suspicion represents the type of citizen vigilance that can save American lives, law enforcement officials insist.

"The ability to make a chemical or biological device that could be so devastating or an actual explosive, it really does require policing law enforcement to try to find ways to work with the public to be our eyes and ears," Bratton told FOX News.

Two years ago, the LAPD created a system to help police report potential terrorist activity to the right federal agencies, an initiaitive that has led to dozens of substantive investigations. iWatch is a civilian version of the program.

"We want people to report and we want people to feel comfortable reporting, so let the experts decide, we know what we're looking for so never be shy about reporting. And the great thing now is we have a mechanism to report," McNamara said.

Click here for the Web site iWatchLA.org.

FOX News' Anita Vogel contributed to this report.

The Associated Press contributed to this report.