A gunman has taken one person hostage inside the headquarters of the Discovery Channel in Maryland and fired several shots Wednesday, US media reported.

The man, believed to be an Asian, was possibly carrying explosives, police said, according to ABC News.

'We have reason to believe there is an armed gunman at One Discovery Place. All employees should seek protection in a locked office on their respective floors immediately,' read an email sent to employees and read over the public address system.

The man entered the lobby and said, 'Nobody is going anywhere,' local television WJLA TV reported.

The area surrounding the building was sealed off and FBI agents, including explosives experts, rushed to the building.

The Discovery Channel headquarters in Silver Springs, Maryland, is located just outside Washington. The building also houses a daycare centre, which was evacuated.