GAITHERSBURG, Md. (WUSA9) -- Firefighters battled a three-alarm fire in Gaithersburg on Tuesday morning.
Sky 9 flew over the scene at 40 Upper Rock Circle. Video showed heavy fire through the roof of a building.
SEE PHOTOS OF THE FIRE HERE: http://on.wusa9.com/1pEgjOR
Montgomery County fire officials tell us there was a roof collapse.
We're told the four-story building was not occupied. Montgomery County fire spokesperson Pete Piringer tweeted that the apartment complex is the Gables Upper Rock Apartments, and the building is under construction.
There are 200 firefighters at the scene and a number of trucks, engines and other equipment.
No injuries have been reported but the fire has destroyed 150 apartment units that were near completion and were scheduled to open in a couple of weeks.
Road closures remain in effect.
At approximately 6:50 a.m. we were told most of the fire had been knocked down.