Franklin, MA – A propane gas leak is to blame for an explosion last year that killed two people in a Franklin condominium, investigators said Wednesday.

State Fire Marshal Peter J. Ostroskey’s office said in a news release that “there is nothing to indicate any criminal or intentional act took place to cause the explosion.”

Nancy and Richard Brown died in the Oct. 10, 2015 explosion.

The news release, issued jointly by Franklin Fire Chief Gary B. McCarraher and Franklin Police Chief Thomas Lynch, said the blast occurred when an unknown source ignited gas that had been leaking into the home. The propane may have come from the heating system or a gas fireplace, officials said.

The Browns, both 66, had recently moved from Florida to be closer to their grandchildren.