A fire that killed three horses in Amherst, Massachusetts, on Sunday could have been caused by rags used in painting projects.
The blaze at Muddy Brook Farm destroyed most of a barn, workshop and apartment. Three people and six horses made it out safely.
The Massachusetts Department of Fire Services arrived Sunday morning to investigate.
Spokeswoman Jennifer Mieth said the cause is believed to be accidental, but it has not been determined.
"My understanding is that there was a bucket of rags that had been used in painting and staining projects, which is quite often a cause of spontaneous combustion fires," Mieth said.
After a fire at Palmer High School last March, the department said spontaneous combustion of rags soaked in linseed oil was the cause.
Mieth said oily rags should be spread out to dry. Otherwise, the chemicals can create their own heat and ignite the material.
The Department of Fire Services has provided detailed guidance on the safe disposal of rags used in painting and staining work.