DAYTON, Ohio -- Firefighters in Dayton said a sprinkler system may have saved an entire apartment building from burning to the ground.

The fire happened Monday at the DMHA Westdale Terrace high rise on Melba Street. By the time firefighters arrived, the sprinkler system was already working.

Firefighters said the fifth floor apartment, where the fire started did not have a tenant living there, so arson investigators are trying to determine what started the fire.

Residents said they are thankful for the people who helped save their lives.

Authorities said other apartments suffered some water damage, but the fire was contained to the one apartment.