The paragraph describes the events of the Great Chicago Fire in chronological order. It explains that Daniel Sullivan first noticed flames in the O'Leary barn around 8:30pm on October 8th. By 9:30pm the entire block was ablaze. Within 3 hours, fires had spread across Chicago, fueled by strong winds from Lake Michigan. It took another full day to extinguish the fire, during which over 17,500 buildings were burned.