A fire that displaced a Roanoke County couple and their dog Sunday night has been ruled accidental, a fire department spokeswoman said.

Fire investigators were unable to determine the exact cause of the fire in the 3500 block of Simsmore Avenue because of the extensive damage to the storage building where the fire began, Jennifer Conley Sexton said. The house is likely a total loss. Damage estimates are about $125,000.

Firefighters were called to the modular home in the Mount Pleasant area about 8 p.m. A man who lives at the home reported that his storage building, next to the house, was engulfed in flames.

When firefighters arrived, the modular home had also caught fire, Conley Sexton said. The man and his wife -- the identities of whom were not released -- and their dog were not injured.

It took firefighters from the Mount Pleasant, Clearbook, Vinton and Cave Spring stations several hours to put out the blaze. The storage building contained lawn mowers and tools, and was hooked up to electricity, Conley Sexton said.

The couple are staying with family members, Conley Sexton said.

-- Amanda Codispoti