Washington, Sep 2 (IANS) An armed man who took three hostages at the Discovery Channel headquarters and was killed by police after a tense four-hour standoff told a TV channel that he had bombs strapped on 'ready to go off'.

The gunman spoke to an NBC producer for about 10 minutes during the siege Wednesday of the Discovery building in the Washington suburb of Silver Spring in neighbouring Maryland.

NBC said the producer called the building and was surprised to suddenly be speaking to the gunman, who identified himself as James Jay Lee, and said, 'I have a gun and I have a bomb. I have several bombs strapped to my body ready to go off.'

NBC did not reveal the conversation until the hostage situation had been resolved.

Police spent several hours negotiating with Lee, who was upset about the network's programming, after he burst into the building about 1 p.m. waving a handgun and with canisters strapped to himself.

Montgomery County police chief Thomas Manger said one explosive device detonated on the gunman's body when they shot him, and they were working to determine whether two boxes and two backpacks he also had with him were explosives. The 1,900 people who work in the building were able to get out safely.

Manger said officers were monitoring Lee on building security cameras and tactical officers moved in when they saw him pull out the handgun and point it at one of the hostages. Three hostages were released safely.

During the negotiations, Lee exhibited a 'range of emotions', Manger said. At times he was agitated and at times he was calm, but he never strayed far from his grievance against Discovery, he said.

Discovery Channel spokesman David Leavy said company officials were familiar with Lee, who had protested at the network in 2008, but the company 'did not take his threats or demands seriously.'

He then wrote he had a grudge with Discovery because they ignored his ideas for a TV show. At that protest, Lee was fined $500 for throwing money into the air and being arrested at the demonstration.

Lee was linked to a manifesto that was posted on the internet, CNN said, citing a source close to the investigation.

The angry 1,149-word manifesto said in part, 'Humans are the most destructive, filthy, pollutive creatures around and are wrecking what's left of the planet with their false morals and breeding culture.'

The writer demanded that the Discovery Channel broadcast daily prime-time shows devoted to 'solutions to save the planet,' perhaps in a game-show format, and insisted, 'Make it interesting so people watch and apply solutions!!!!'

(Arun Kumar can be contacted at arun.kumar@ians.in)