Residents of a quiet Ashburn, Va., neighborhood were stunned Wednesday, as federal agents raided the home of 34-year-old Farooque Ahmed over suspicion that he'd been planning a terrorist attack.

Authorities said Ahmed was planning to bomb four busy Washington, D.C., train stations near the Pentagon in an effort to kill as many U.S. military personnel as possible.

The FBI learned in January that Ahmed -- a Pakistani-American -- wanted to go overseas to fight against the United States, and had been following him since.

"The FBI was aware of Mr. Ahmed's activities before the alleged attempt began," D.C. Metro Transit police chief Michael Taborn said.

CBN News Terrorism Analyst Erick Stakelbeck has more on the investigation against Farooque Ahmed.  Click play for his comments, following Efrem Graham's report. 

The plan was to have bombers use rolling suitcases full of explosives aboard trains, and simultaneously set them off during rush hour sometime next year.

"I'm shocked. I never would have expected it out of them," said neighbor, Barbi Shires. "I've seen them a few times. They kind of kept to themselves. They were nice."

Agents said Ahmed surveiled D.C. subway stations in July and August. He then gave the recordings to someone he thought was an al Qaeda operative -- but instead was an undercover agent.

"It's crazy that we live in a day and time where people will threaten to do crazy things for nothing," said D.C. commuter Jarrell Taylor.

Though commuters were shocked, investigators insisted Ahmed posed no real danger.

"I want to make myself perfectly clear that at no time were any patrons, employees or facilities associated with the Washington Metro Transit System in jeopardy from the activity on the part of this young man," Tabron said.

Ahmed was arrested as he allegedly tried to hand off more subway surveillance photographs.