A fast-moving fire that spread throughout a Suffern apartment building overnight Monday displaced 70 people.

Fire officials say that the fire started in an apartment on the top floor and then began to spread. Fast-responding firefighters and police were able to force out dozens of families and contain the damage to two apartments.

Suffern Fire Chief Clark Osborne says a smoke and fire alarm made all the difference for what could have been a potential tragedy.

?If that had not gone off, it would have been much more severe,? says Osborne. ?Obviously it?s an older building ? fires can spread quickly.?

Some of the displaced residents are staying with landlord David Shin temporarily until they can return home.

The Suffern apartment building is closed until it is deemed safe by a building inspector. The cause of the fire is still under investigation. No one was hurt.