WASHINGTON — A large house in Montgomery County is a total loss after it was engulfed in flames Monday afternoon.

A more than 6,300 square-foot house at 14001 Gorky Drive in Potomac caught fire around 2 p.m. By the time firefighters responded, the flames had already moved from the garage up to the roof, said Montgomery County Fire & Rescue spokesman Pete Piringer.

During the fire, the attic collapsed, engulfing the entire residence in flames. The house is a total loss, Piringer said, adding that he estimates the cost of damage to be “in the neighborhood of $1 million.” The house was valued at $1.18 million in January, according to state records.

No one was in the house at the time of the blaze. Two pet dogs died in the fire, Piringer said. There were no other injuries.

About 65 firefighters responded to the scene and it took them about an hour to completely knock out the fire.

“Initially, this area was believed to be a non-hydrant area, but fortunately there were some fire hydrants in the area so firefighters were able to quickly deploy their water supply with large-diameter hoses,” Piringer said.

The cause of the fire is still under investigation, but Piringer says it looks like it started in or around the garage.

Below is a map with the location near the fire:

WTOP’s Michelle Basch contributed to this report.