What was the Great Molasses Flood of 1919?

"An unusually warm winter day resulted in 2.3 million gallons of molasses flooding the North End neighborhood of Boston, Massachusetts. The disaster killed 21 people and injured 150 others. Rescue missions were launched to save people from the sticky and deadly mess, led by the Red Cross, the army, the navy, and the Massachusetts Nautical School. With the help of hundreds of volunteers over the course of several weeks, the streets were cleaned up. But the smell of molasses and the horror of the preventable tragedy lingered for decades to come"--Provided by publisher.