Eight families, totaling close to 20 people, have been displaced following a fire Saturday night at a Norwalk apartment building, fire officials say.

It happened on Elmcrest Terrace just after 11 p.m.

The initial call came in for smoke on the second floor.

Officials say firefighters found heavy fire engulfing the first and second floors in the front of the building, with residents possibly trapped. A third alarm was immediately declared and all 34 of the city's on duty firefighters were called to the scene.

Due to the amount of fire in the front of the building, firefighters had to use ladders and go through windows to get inside and search for people.

The fire was contained to the front portion of the building on the first and second floors, according to authorities. Officials say because residents had closed the doors to the apartments, that prevented the fire from spreading to the entire building.

The building suffered severe fire, smoke and heat damage.

Four people were evaluated by Norwalk EMS but refused treatment.

The cause of the fire is under investigation.