UPDATE 2:25 All workers in building were evacuated. Many told to go home though they left personal items in the building.
UPDATE 2:21: Police are saying there is at least one hostage.
UPDATE 2:15 p.m. Angela Gates, a Metro spokeswoman, said the SIlver Spring Metro station remains open, though the south entrance is closed. Buses that service the Silver Spring Transit Center are being detoured around closed streets, she said. Colesville Road is blocked off.
UPDATE: 2:02 p.m.: The Discovery Channel day care has been evacuated to the nearby McDonald's. The day care had about 100 kids. They are reported to be safe.
UPDATE: 1:50 p.m.: According to Cpl. Dan Friz, a Montgomery County police spokesman, a tactical team is trying to get in touch with the gunman, who is being monitored on closed circuit TV.
The "tactical team has put together a plan for dealing with this individual," Friz told ABC 7 News.
Friz was unable to confirm reports that multiple shots have been fired, but he said no shots had been fired by police as of 1:40 p.m.
Police were initially dispatched to the building for the report of shots fired at about 1 p.m. Police are reporting the suspect is an Asian male.
"Some sort of device on him that may be explosive in nature..." Friz said.