EAST RIDGE, TN. (WRCB) -- A burglar alarm alerted East Ridge authorities to a house fire, that nearly destroyed one family's home Friday afternoon.

It wasn't until the alarm sounded that neighbors noticed smoke. By that time, fire crews were already on scene.

"Officers arrived on the scene to investigate the alarm and found smoke coming from the house," says Erik Hopkins, with the East Ridge Police Department.

Officers quickly realized it wasn't a burglar who shattered the windows of the duplex on Martha Avenue, but the intense heat of a fire inside.

"After the fire was extinguished, it was determined those windows were broken by the fire itself," says Hopkins.

The family was not home at the time.

The Red Cross has stepped in to give them a place to stay, as fire investigators try to pinpoint what sparked the fire.

"Damage was fairly extensive," Hopkins says. "Damage was estimated around $35,000."

Hopkins says it's the first time he can remember an alarm system alerting fire crews.

But the broken windows may have been what kept the entire duplex from burning to the ground.

Arson and fire investigators are still working to determine what started the fire.