Video: 'The Fire Begins — The Great Chicago Fire: A Chicago Stories Special'

(Sunday, October 8, 1871, about 8:30 p.m. local time; during the Great Chicago Fire) — The Great Chicago Fire, a conflagration that burned in the American city of Chicago over three days, started tonight in or around a small barn belonging to the O’Leary family that bordered the alley behind 137 DeKoven Street, a neighborhood southwest of the city center.

Video: 'Lessons from History: The Chicago Fire of 1871'

The shed next to the barn was the first building to be consumed by the fire.

The fire killed approximately 300 people, destroyed more than 17,000 buildings across roughly 3.3 square miles of the city, and left more than 100,000 residents homeless.

City officials never determined the cause of the blaze, but the rapid spread of the fire due to a long drought in that year’s summer, strong winds from the southwest, and the rapid destruction of the water pumping system, explain the extensive damage of the mainly wooden city structures.