The fire at a three-story building on Sherman Street Tuesday afternoon that displaced 16 residents was caused by improperly discarded smoking materials, fire officials said Wednesday.

The fire was determined to be accidental, said Portland Deputy Chief Keith Gautreau.

Flames began on the second floor rear porch, where the smoking materials, fanned by high winds, ignited a fire that spread quickly through a nearby door and window to the building’s interior, Gautreau said.

Residents said the building was part of a network of homes for substance abuse recovery run by the Oxford House.

The Red Cross of Southern Maine is assisting 14 of the 16 people with temporary shelter, and the remaining two residents made arrangements with family or friends, Gautreau said.

Oxford House is a nonprofit that operates self-help sobriety houses across the United States, including 13 in Maine.

Eight houses are in Portland, including the Sherman Street house, according to the Oxford House website.