Lowell firefighters extinguished a four-alarm blaze Sunday morning at a part residential, part commercial building on High Street.
The fire broke out around 9 a.m. at the structure at 69 High Street. The building, which has seven residential units and three commercial units, is at the intersection of East Merrimack Street. Fire officials credited an alarm system with alerting occupants to evacauate the building. No resident was injured but two Chelmsford firefighters were treated for minor injuries to their hands and ankles.
The fire reportedly broke out on a rear porch area and quickly spread. At one point, much of the roof was on fire.
Fire officials said the construction of the building made it difficult for crews to reach the fire and extinguish it.
The cause of the blaze remains under investigation. The Red Cross is assisting residents who were displaced by the blaze.