A gunman shot to death by police after he took hostages at Discovery Channel headquarters said he hated the company's television shows because he claimed they promoted population growth and environmental destruction.

Three hostages _ two Discovery Communications employees and a security guard _ escaped unhurt after the four-hour standoff Wednesday in Silver Spring, just outside Washington. After several hours negotiating with the gunman, tactical officers moved in when authorities monitoring him on building security cameras saw him pull out a handgun and point it at a hostage, said Montgomery County Police Chief Thomas Manger.

A law enforcement official speaking on condition of anonymity because the investigation was ongoing identified James J. Lee as the suspect.

It wasn't the first time Lee, a homeless former Californian, had targeted Discovery's headquarters. In February 2008, he was charged with disorderly conduct for staging a "Save the Planet Protest." In court and online, he had demanded an end to Discovery Communications LLC's shows such as TLC's "Kate Plus 8" and "19 Kids and Counting."

Instead, he said, the network should air "programs encouraging human sterilization and infertility."

"Humans are the most destructive, filthy, pollutive creatures around and are wrecking what's left of the planet with their false morals and breeding cultures," Lee wrote in a bitter manifesto on his website.

Lee, 43, also objected to Discovery's environmental programming. He wrote in 2008 that a show called "Planet Green" was "about more PRODUCTS to make MONEY, not actual solutions."

Police say the gunman burst into the building about 1 p.m. and took hostages in the lobby on the first floor. A gun wasn't his only weapon, as an explosive device on his body detonated when police shot him, Manger said. Police were trying to determine whether two boxes and two backpacks the gunman had also contained explosives and authorities sent in a robot to disarm a device on the gunman's body.

NBC TV News reported that after its producers called Discovery's phone number, a man identifying himself as James J. Lee got on and said he had a gun and several bombs.

"I have several bombs strapped to my body ready to go off. I have a device that if I drop it, if I drop it, it will ... explode," the man told NBC.

Police Capt. Paul Starks said the suspect had shot a gun at least once and that authorities believe he was acting alone but were investigating all possibilities.

Lee's mission against the Discovery Channel goes back at least a few years. In the February 2008 protest in which he was arrested, he threw fistfuls of cash in the air and paid homeless people to carry signs condemning the network. Police found his pockets stuffed with more than $20,000, according to court records.

Lee served two weeks in jail after his arrest during which doctors evaluated his competency to stand trial. County State Attorney John McCarthy said Lee was ordered to stay 500 feet away from Discovery headquarters as part of his probation, which ended two weeks ago.

Lee faulted the Discovery Channel for shows as varied as "Future Weapons," "It Takes a Thief" and "Planet Green." Instead, he sought programming based on "My Ishmael," a book by philosopher Daniel Quinn in which a telepathic gorilla instructs a 12-year-old girl on society's failings. On his MySpace page, Lee said his heroes were Quinn and "Star Trek" commander James T. Kirk.

Quinn said in an interview from his Houston home that Lee misinterpreted his book's message about the folly of continually increasing food production to meet population demands.

The author said he hadn't heard of Lee before Wednesday but called his death "pretty horrible." Had he been able to speak with him, he would have told Lee "he's giving a bad name to the ideas that he's trying to espouse."

Lee in 2008 also held a related contest promising $200,000 worth of Hawaiian real estate for the best essay proposing a save-the-planet TV show.

The Maui News and KHON-TV reported that Lee had lived in the Lahaina area of West Maui. The newspaper reported that he was a 1985 graduate of Lahainaluna High School and his former classmates and principal described him as a normal person who didn't cause any trouble.

"As far as I'm concerned, he was a good kid," former Lahainaluna principal Henry Ariyoshi told The Maui News.

None of the 1,900 people who work in the Discovery Channel building were hurt Wednesday.

"We're relieved that it ended without any harm to our employees," said David Leavy, Discovery's executive vice president for corporate affairs.

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Associated Press Writer Kathleen Miller and Associated Press Photographer Jacquelyn Martin in Silver Spring; Matthew Barakat in Rockville, Maryland; Matt Apuzzo, Eileen Sullivan and Nafeesa Syeed in Washington; Ben Nuckols in Baltimore; Ramit Plushnick-Masti in Houston; and Jacob Jordan in Atlanta contributed to this report.