Massachusetts fire marshal reports the Gabriel House fire that killed 10 and injured over 30 was accidental, possibly sparked by a resident smoking or a mechanical issue.

The July 13 fire killed 10 people and injured at least 30. Its exact cause might never be determined, officials said.

The deadly fire at an assisted-living facility in Fall River, Massachusetts, was accidental, however, the cause is classified as undetermined because investigators found two possible origins, officials said.