Killeen, Texas ? Ultimately, it was the keen eye of a Texas gun shop clerk that helped authorities find an AWOL soldier who’d stashed bomb-making material in his nearby motel room for a planned attack on Fort Hood soldiers.

The tip that led Killeen police to Pfc. Naser Abdo on Wednesday prevented what could have been the second terrorist attack on the Army post, following a 2009 shooting rampage in which an Army psychiatrist is charged with killing 13 people. Earlier this year in Texas, a shipping company that told the FBI about a suspicious order for a chemical explosive foiled an alleged plot to blow up former President George W. Bush’s Dallas home.

The enduring lesson for a post-9/11 world: America’s workforce plays a crucial role in preventing potential terror attacks.

“A vigilant public and informed local law enforcement make it much more complicated for people wishing to carry out attacks to do so,” said John Cohen, principal deputy counterterrorism adviser at the Homeland Security Department.

Federal and local law enforcement agencies have established programs over the past decade that encourage the public to report suspicious activity and tips from businesses have led to multiple high-profile arrests.

Abdo, 21, who went absent without leave from Fort Campbell, Ky., early this month, was arrested Wednesday at a motel outside Fort Hood and charged with possession of an unregistered destructive device. Police say he was perhaps only a day away from unleashing bombs in a restaurant frequented by soldiers and attacking the Army post.

Abdo’s alleged plan was cut short when Guns Galore employee Greg Ebert became suspicious after the soldier acted oddly while purchasing smokeless gunpowder, shotgun ammunition and a semi-automatic pistol magazine. Ebert’s call to police and the soldier’s subsequent arrest was a proud moment for employees of the store — the same place Maj. Nidal Hasan bought a pistol used in the Fort Hood shooting spree two years ago.

Store clerk Dave Newby said Hasan’s purchase, while legal, devastated store workers and put everyone on higher alert.

“I think we all changed,” he said. “It was terrible. We thought about coulda, shoulda, woulda.”

The retired police officer said Abdo arrived at the Killeen gun shop in a taxi — unusual for the Central Texas town — and proceeded to buy 6 pounds of smokeless gunpowder, while asking what it was. Abdo didn’t say much as he paid in cash, and he didn’t bother to collect his change or a receipt before returning to the waiting taxi.

“Now, he hasn’t done anything unlawful — it doesn’t prevent me from being curious,” said Ebert, who retired from the police force last year.

Federal authorities say actions like Ebert’s can keep America safe.

“The willingness of an individual to contact law enforcement about an event or incident that may be indicative of a possible threat is vital to our mission,” FBI spokesman Paul Bresson said. “It may turn out not to be a threat but at least we have the opportunity to check it out.”