WASHINGTON — A massive fire gutted an apartment building in a dense area of Rockville Tuesday morning.

A large three-alarm fire broke out at Gables Upper Rock Apartments, located at 70 Upper Rock Circle in Rockville at about 4:15 a.m. The fire closed Shady Grove Road between I-270 and Md. 355 for several hours.

The road reopened in both directions by 10:15 a.m.

The apartment building is under construction, according to Montgomery County Fire and Rescue Spokesman Pete Piringer. The 150-unit apartment building was nearly complete, but no one was living there yet.

Crews controlled the fire by about 6:45 a.m. and no injuries have been reported, Piringer says. Some flames and smoke were visible from nearby I-270 for most of the Tuesday morning commute.

Piringer says when firefighters arrived at the apartment building early Tuesday, they found heavy fire coming from the upper floors of the four-to-five story building. About 200 firefighters responded to the fire, Piringer says.

The fire’s cause is not yet known. Investigators are on the scene.

Fire crews were able to protect many nearby buildings from damage in the dense area, Piringer says.

The Substance Abuse and Mental Health Services Administration, located next to the apartment building, is closed Tuesday because of the blaze.

The cost of damage caused by the fire is not yet clear, but Piringer calls it “extensive.”

Watch videos of the flames and the scene below:

The Associated Press contribute to this report.