CHELSEA, Mass. — At least 16 people have been displaced as firefighters continue to battle a fire that has engulfed three, three-story apartment buildings just outside of Boston.

Firefighters responded to the fire in Chelsea Wednesday afternoon.

Chief Leonard Albanese says they have the fire under control, "but not extinguished."

NBC 10 Boston reports two firefighters have been taken to a hospital with unknown injuries. No residents have been hurt.

The fire broke out around 3:30 p.m. and had collapsed part of one building's roof by the time firefighters arrived. It's unclear how the fire started.

Twenty-five firefighters are on the scene, comprising at least three fire departments. Chelsea is located directly across the Mystic River from Boston.