Manger confirmed that Lee ‘had a history of conflict’ with Discovery Communications, resulting in an arrest in 2008 during a protest outside the premises. Lee also posted assorted online tirades against the company and its assorted channels’ programming, imploring Discovery Communications in one manifesto to ‘stop encouraging the birth of any more parasitic human infants.’

Manger said that during the four-hour standoff, ‘A device did detonate on [Lee's] person.’ It was earlier reported that Lee had entered the building with a handgun and what appeared to be canisters strapped to his back. The building remains an active crime scene, and authorities will be remaining to sweep the headquarters and ensure that it is clean of any potentially harmful items.

Discovery Communications’ EVP of global communications David Leavy also addressed reporters, thanking law enforcement and Discovery security personnel for an ‘incredibly professional operation…We’re relieved that it’s ended without any harm to our employees… All of our employees are accounted for.’ Leavy said that Discovery Communications was ‘cognizant and aware of [Lee] but did not take his threats and demands seriously.’ Leavy also said that the priority in the coming days for the company is ‘going to be nurturing our employees’ needs’ in the wake of the standoff. Adding that he was ‘proud of the Discovery family,’ in praising the company’s strong culture and standards, he summed up the day’s events by saying ‘that strength came through today.’

UPDATE: At a briefing taking place at approximately 3:18pm, Chief Tom Manger of the Montgomery County Police said there is a small number of hostages. The police cannot currently confirm the identity of the hostages, but they say most of the over 1,900 employees within the building have been evacuated. Reports have identified the suspect as James J. Lee. Lee had reportedly been arrested at a protest outside of the Discovery Communications building in 2008. However, Chief Manger said they could not confirm his identity.

ABC7 reports that eyewitnesses have said at least one shot had been fired by the gunman who upon entering the lobby reportedly said, ‘No one is going anywhere.’ Police have told ABC7 that there is a concern that the suspect has explosives on him in the form of tanks or containers strapped upon his back. The day care operated by Discovery in the area was successfully evacuated. We will continue to monitor the situation and update the story as it develops.