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Police fatally shot an armed man who had taken hostages at Discovery Communications headquarters, ending a nerve-rattling standoff that held much of Silver Spring, Md., paralyzed Wednesday afternoon.

Montgomery County Police Chief J. Thomas Manger told reporters that a device went off and released smoke during the confrontation, but that three hostages were safe. He said the man had two backpacks and two boxes and that police were trying to determine early Tuesday evening if they contained explosive devices.

The building, which houses 1,900 Discovery employees, was at least partly evacuated after the man entered the Silver Spring complex. It was unclear whether he fired any shots. People were forced to remain in place for hours as police tried to negotiate with the man through the afternoon.

He was shot around 5 p.m. Wednesday.

NBC said law enforcement sources identified the suspect as James Jay Lee, a longtime protester of the Discovery Channel who was convicted of disorderly conduct in 2008. DCist reported that Lee was arrested at a protest outside the Discovery building on Feb. 21 after reportedly throwing money to draw a crowd.

VIDEO: Flying money in February protest at Discovery headquarters

Court records show that a James Jay Lee arrested on the same date and location was sentenced in March to six months probation and ordered to pay a $500 fine.

His attorney in the case, former public defender Johanna Leshner, told TVGuide.com that Lee dismissed her to represent himself. He also represented himself in an unsuccessful appeal.

The court records describe Lee as a 5'10, 235-pound 43-year-old. They listed a Silver Spring community outreach and support program for the homeless as his mailing address.

The director of homeless services for the center, Interfaith Works, told TVGuide.com on Wednesday that Lee had not received mail there in more than two years.

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On a website called Savetheplanetprotest.com that promoted the February 2008 protest, a man who identified himself as "Lee" called on people to join him in protesting.

"The Discovery Channel produces a lot of shows about saving the planet that all have one thing in common," the site said. "They don't work." The site claimed Discovery promotes pollution, overfishing, and overpopulation, among other complaints.

A phone number for the site was out of service and an email was returned as undeliverable Wednesday.

Thomas Leonard, a man who said he was Lee's brother-in-law, told Fox News that Lee had once had "a small family trust" and had feigned a terminal illness to fool relatives. He said Lee was now estranged from his family.

"He kind of wormed his way out of some of the family's money," Leonard said.

The building is home to several of Discovery's networks, including the Discovery Channel TLC, Animal Planet and the Science Channel. Discovery is planning to launch a cable network with Oprah Winfrey in 2011.