WASHINGTON -- We're learning more about that recent terror plot to strike New York with homemade bombs and how intelligence officials learned about the suspects.
The case is ongoing, but is shedding light on how law enforcement are on the offensive to prevent another attack on the American homeland.
A derailed passenger train in Rhode Island is designed to look like the scene of terror attack, but it's only a drill.
Click play to see the report and an analysis from CBN News Terrorism Analyst Erick Stakelbeck.
Law enforcement and emergency responders around the country train how to react in the event something like this really happens.
They're also working to keep would-be attacks from getting off the ground in the first place.
They were able to do that in the case of Najibullah Zazi, a 24-year-old Afghan immigrant accused of plotting an attack on New York this year on the eighth anniversary of 9/11.
Prosecutors say he was planning to set off homemade bombs made out of hydrogen peroxide and acetone he bought in bulk at a Denver-area beauty supply store.
But the U.S. learned of Zazi's plot through a CIA source and the word was passed through law enforcement agencies.
"The recent case here by way of example gives us all information to share and has been now shared through a product from DHS about the over purchase of certain products that can be used in explosive making," Homeland Security Secretary Janet Napolitano said.
That information filtered through state and local agencies through 72 nationwide "fusion centers," which collect and share information about potential terrorist activity.
The nation's top law enforcement officer told a conference of police chiefs the coordinated effort helped to stop Zazi and prevent scores of people from dying.
Police say the next step is to build a public partnership where ordinary citizens report suspicious activity.
"An educated and trained public can feel more in control of their own lives if they partner with law enforcement to fight against terrorism," said William Bratton, chief of the Los Angeles Police Dept.