Gunman takes hostage at Discovery Channel headquarters

A gunman entered the headquarters of the Discovery Channel today and took at least one person hostage.

A person inside the building in suburban Silver Spring, Maryland, US, said the man had something strapped to his chest and was holding hostages.

Discovery Communications operates cable and satellite networks in the US including the Discovery Channel, TLC and Animal Planet.

Police said the gunman had "concerns" with the Discovery Channel networks.

Montgomery County Police Captain Paul Starks would not say if the man works for Discovery Communications now or worked there in the past.

Montgomery County fire department spokesman Captain Oscar Garcia said three bomb technicians responded to the scene and several more were on their way.

The initial report was of a suspicious package that was possibly explosive, said Mr Garcia.

Police said a tactical team was trying to get in touch with the gunman, who was being monitored on closed circuit TV.

County government spokesman Patrick Lacefield said the hostage-taker was armed and claiming to have an explosive device.

It was unclear how many people were being held hostage, Mr Lacefield said. Police evacuated the building, asked people in nearby buildings to stay inside and blocked off surrounding streets, he said.