The fire started around 6:15 p.m. Sunday at 1049 Main St., in Peekskill, according to the Peekskill Fire Department.
Arriving firefighters found heavy fire on the third floor, the fire department said.
Several additional fire departments were called in to help bring the fire under control within an hour of arrival, the department said.
The building, which contained several apartments, and a bakery was heavily damaged.
At least 12 people were left displaced, Red Cross officials were on the scene helping with temporary living arrangements.
Departments assisting Peeskill included Mohegan Firefighter Assist and Search Team, Montrose, Peekskill Volunteer Ambulance Corps, and the Buchanan Fire Department.
No injuries were reported.
The cause of the fire is under investigation.
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