OTTAWA -- Four people remain unaccounted for after a home burned to the ground Sunday night southwest of Kemptville.

The fire at the log cabin on Stone Road near Oxford Mills broke out around 6 p.m. on Sunday. Fire officials said the home was fully engulfed in flames when crews arrived and it collapsed quickly.

North Grenville OPP said four people remained unaccounted for Monday morning.

North Grenville fire chief John Okum says the fire was knocked down fairly rapidly but crews remained on scene for several hours.

The fire destroyed the home and the intense flames appear to have spread to nearby vehicles in the driveway.

The Ontario Fire Marshal's office and the Ontario Provincial Police have been called in to sift through the debris in search of answers.

"The investigation will be ongoing. There's no indication at this time the cause of the fire," Okum says.

Neighbours were distraught as they walked by the scene Monday. They said the homeowners, a couple in their 60s, were kind and caring people who had built the three-storey log home in the 1980s and had lived there ever since.

Investigators will likely remain on scene for several days as they continue to try and find out what caused the blaze.