About two dozen residents of a Cambridge building have been forced out of their homes following a fire.

The sound of a fire alarm sent the people living in 12 apartments into the street just after 5 p.m. early Thursday evening.

"I ran, I grabbed my cat, [and I] threw him in my car," says resident Ronnie Walsh.

Nick Pluim was also home at the time, "There was a big cloud coming down the hallway. It was quite scary, so I ran in and rounded up my four month old and ran outside and sat in the cold."

When firefighters arrived at the Langs Drive building they found one unit engulfed in flames. The intense heat had blown out an exterior window.

The building was safely evacuated and crews began to fight the smoky blaze.

A firewall and fire doors prevented the spread of the smoke through the building, but a dozen units were damaged to the point that residents cannot be allowed back in for the moment.

Some of the units below the apartments are occupied by social service agencies which have been impacted as well.

"There's not substantial damage. [There's] a little water damage in one unit. There's some smoke smell," says Bill Davidson of the Langs Farm Village Association.

Cambridge Fire Prevention Officer Eric Robinson says "The fire is still under investigation but they suspect that there was faulty wiring or a faulty appliance that may have caused the fire."

Electrical issues with a television and some extension cords are a focus of the investigation.

"They are going to have to bring the ceiling down [and] paint the walls, but the unit itself is going to have to be completely re-done," Robinson adds.

Crews are beginning the cleanup and the Electrical Safety Authority is scheduled to inspect the burnt out unit on Monday.

The displaced residents were permitted to retrieve some personal items, but have been temporarily relocated by the Red Cross. It will likely be a few days before they can return home.

"They've given us food vouchers [and] tons of stuff. So they've been a big help," says Pluim.

No one was injured but damage is estimated at about $200,000.