Rubble is all that remains of a nearly 160-year-old Putnam Valley home that went up in flames Monday night.

A neighbor walking his dog saw the fire at 15 Canopus Hill Rd. before 11 p.m. and called 911.

While firefighters were able to quickly bring the blaze under control to stop it from spreading, they were unable to put out the intense flames until 4 a.m.

They believe the blaze started in the older part of the home that dates back to the 1800s and spread to the newer construction.

Fire officials said the owners were away on vacation and a housekeeper was the last person inside the residence about five hours before the fire.

According to Putnam Valley Fire Department Chief Bruce Johnson, the damage is so extensive, investigators may be unable to determine the cause of the fire. Officials still want to question the housekeeper.