Update, 10 a.m.: The fire caused an estimated $1.45 million of extensive structural damages to the house on Query Mill Road, said Montgomery County Fire and Rescue spokesman Capt. Oscar Garcia.

The bulk of the fire was extinguished by 6:20 p.m. Wednesday. But crews remained on the scene throughout the night dealing with several hot spots. The second floor collapsed completely.

Approximately 60 firefighters were dispatched from nine local stations to assist in firefighting operations, Garcia said. Crews came from Rockville stations 33, 31 and 23, from Germantown Station 29 and 22, from Gaithersburg Station 8, from Cabin John Station 10 and from Upper Montgomery County Station 14.

A man, woman and dog were residents of the house and have now been displaced as a result of the fire. The man was the only resident on the scene when fire and rescue crews arrived on Wednesday, Garcia said.

Investigators were not able to enter the house until Thursday morning and they continue to search for a cause.

Correction: An earlier version of this story incorrectly stated the dog was missing. The dog is safe with the house owners, Garcia said. Also, the earlier version incorrectly identified the number of occupants at the house at the time of the fire.

Update, 9 p.m.: The fire has caused "extensive and significant" damage to the house, said Montgomery County Fire and Rescue spokesman Capt. Oscar Garcia. Although the total cost of damages to the house is not yet known, Garcia estimated it will be close to a million dollars.

The cause of the fire is still under investigation. Officers were interviewing the two adult residents on Wednesday night, Garcia said.

No injuries have been reported.

Original post, 6:50 p.m.: Montgomery County Fire and Rescue are on the scene of a significant house fire in the 13000 block of Query Mill Road in North Potomac.

Police and Fire were called to the scene at 5:11 p.m. Wednesday. Fire and Rescue spokesman Capt. Oscar Garcia said the occupant was outside the house when Fire and Rescue arrived. No injuries have been reported.

The house is in an area with no municipal water, so water tanks had to be brought in, Garcia said. No houses are close enough to the fire for the flames to spread, and the fire is ongoing.