Contractors doing demolition work at a Winchester house found more than old timbers when they stumbled across human remains.

The Middlesex district attorney’s office said the strange discovery happened Thursday, Nov. 5 just before 12:30 p.m. No further information about where on the Dartmouth Street property the bones were found.

The state’s chief medical examiner confirmed that the bones are indeed human remains. The district attorney’s office said in a statement posted to its website that “preliminary information available suggests there may be multiple skeletal remains that appear to have been there for an extended period of time, possibly over 100 years.”

The Winchester Star first reported the find.

A frequently-asked questions document posted by the Massachusetts Historical Commission states that many unmarked graves exist across the state. They are often pre-colonial or colonial Native American burials that were never marked or whose markers were lost to history, or newer non-Native burials whose markers met the same fate.

If construction work turns up human remains, state law stipulates that the bones not be touched or disturbed. Instead, local police and the medical examiner must be notified; they may also call in the office of the state archaeologist, which investigates remains over 100 years old.