Excerpts from abc7chicago.com:

A fire that broke out at a home in Northbrook Wednesday morning had three families running for their lives. An off-duty firefighter was on his way to work when he spotted a home in the 2500-block of Melanie Lane fully engulfed by flames. The Northbrook Fire Department was on the scene about 8 minutes later. Helicopter footage shows fire billowing out of the home and spreading to the houses on either side of it.

The woman who owns the home where the fire started said she heard a loud pop, then saw a wall of flames and managed to escape relatively unharmed. The neighbors got out too.