STOW — Two recent fatal fires in Massachusetts are being blamed on smoking.

The state Fire Marshal on Thursday said a blaze at a duplex in Northbridge on Saturday that claimed the lives of two young women, and a May 7 fire in Fall River that took the life of a 61-year-old man, were both the result of "the improper disposal of smoking materials."

Investigators say the Northbridge fire started on the couch in a first-floor living room. Fire Marshal Peter Ostroskey says there is no evidence the home had working smoke or carbon monoxide alarms. The victims' names have not been released by authorities but relatives say they are both 22 years old.

The Fall River fire started on a reclining chair located in the kitchen of Emile Saucier's third-floor apartment.