An overnight fire ravaged a pair of multimillion dollar beachfront houses in Stone Harbor. A third house also was damaged by the blaze.

None of the Cape May County houses was occupied at the time.

Estimates reported in the media have listed the property loss at $5 million to $10 million.

Firefighters were called to East 104th Street after reports of the fire just after 12:30 a.m. The fire spread to two other homes.

A 911 call from a passerby who was walking a dog is being credited with alerting firefighters, who needed about an hour and a half to get the fire under control.

"Most likely the cause is a heating system that people leave on during the winter months that keeps the pipes from freezing," said Stone Harbor Fire Chief Roger Stanford.

No injuries were reported.

The fire marshal is expected to be on the scene this morning to try to determine a cause.

Contact Gene D'Alessandro at 215-854-2443 or gdalessandro@phillynews.com.

This article contains information from the Associated Press.