The investigation is underway into the cause of a three-alarm fire in Montrose that heavily damaged a historic home on Lake Avenue May 4.

Officials say the home-owner, Sarah Bertsch, who is reportedly in her 90s, escaped unharmed.

Bertsch was apparently alerted to the blaze by smoke detectors.

Some landscape workers reported the fire at around 2:45 p.m.

Family members say the house was built in the 1850s.

It’s believed the fire started on the first floor and spread through the second floor and into the attic.

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