Police have shot dead an armed man who took three people hostage at the Discovery Channel's headquarters Wednesday. All the hostages escaped safely.

Police spent several hours negotiating with the hostage taker after he burst into the suburban Washington building, waving a handgun and with canisters strapped to his body.

A law enforcement official said authorities had identified James J. Lee as the likely suspect. In 2008, Lee was arrested after throwing money into the air in a protest outside the Discovery building.

Police said an explosive device may have detonated, and the suspect may have brought other devices into the building. Nearly 2,000 people who work in the building were able to get out safely.