Authorities say a fire that destroyed a conference room at the Massachusetts State Police Museum and Learning Center was caused by the spontaneous combustion of oily rags.
The fire at the museum in Grafton was reported about 9:30 p.m. Saturday. State police say it was contained to the second floor, mainly in the conference room. There were no injuries.
Artifacts and photographs from the department's 151-year-history were in first floor display cases that sustained some smoke and water damage. Authorities say the items can still be viewed by the public.
The State Fire Marshal says workers were at the museum Saturday refinishing wooden molding on the conference room. Oily rags covered in sawdust were left in a plastic bag at the end of the day.
Those rags combusted, causing the fire. The building is not equipped with sprinklers.
State police say they're "grateful beyond words" to firefighters who preserved the memorabilia.