No word on the cause of the blaze in which at least 10 people were injured, six of them seriously.
Four firefighters and one other emergency worker have been hospitalized as well.
Fire Department official Seth Andrews says flames burned in the basement and first floor of the building.
Crews spent two hours putting out the fire.
A hospital official Jill Brookner says five children and one adult were taken to hospital.
She says their conditions are unknown, but two were to be taken to a burn unit for further treatment.