Police say the gunman, who is identified as James Lee, who took three people hostage at the Discovery Channel building, was killed after they shot him. All three hostages were alive and well, and safe.

Police spent the afternoon negotiating with Lee after he entered the Washington building around 1 p.m, carrying a handgun and canisters attached to his body.

Montgomery County Police Chief Thomas Manger says an explosive device may have detonated, and the suspect may have brought other devices into the building. The 1,900 people who work in the building were able to get out safely.

Before he was killed Lee, released this set of demands to the Discovery Channel.