Gunman shot after taking hostages at TV station

A man who took three people hostage at the Discovery Channel's headquarters was shot dead last night after a four-hour stand-off with armed police.

The hostage-taker, named as James Lee, had entered the broadcaster's building in Washington armed with a gun and with a number of canisters strapped to his body feared to be filled with explosives.

Police opened fire when officers saw him pull out a handgun and point it at one of the hostages. All three hostages escaped unhurt but the gunman died shortly afterward.

Thomas Manger, the Montgomery County Police Chief, said an explosive device strapped to the gunman detonated when he was shot. Officers at the scene were trying to determine whether two boxes and two backpacks he had with him also contained explosives.

He said officers had been able to monitor Lee during the siege on the building's security cameras. Lee had previously targeted Discovery with a web campaign and in 2008 staged a protest outside the offices. He had paid homeless people to join his demonstration, and then tossed thousands of dollars into the air.

He walked into the building yesterday at lunchtime and pulled out a gun before taking three people hostage. During negotiations he made several demands which are thought to have been related to his earlier campaign intended to force the channel to do more to help the environment.

Among the demands he made on the web before the siege were for Discovery and other broadcasters to commit themselves to helping to prevent global warming, stop animals being driven into extinction, and to reduce both pollution and the human population.

On a MySpace page he left messages including: "Lee says: It's time for REVOLUTION!!!" In one he ranted: "Civilisation must be exposed for the filth it is. That, and all its disgusting religious-cultural roots and greed. Broadcast this message until the pollution in the planet is reversed and the human population goes down!"

Adam Dolan, a sales director in Discovery's education division, said he was heading to lunch when he was ordered to go to the top floor, lock the door and turn off the lights. Eventually the workers were herded down a stairwell and told to go home: "Everyone was very scared."