343: Number of firefighters killed in the Sept. 11, 2001, terrorist attacks

27: Number killed April 17, 1947, in fires aboard two ships docked in Texas

21: Number killed Dec. 22, 1910, in a fire at a Chicago stockyard

19: Number killed July 29, 1956, at an oil refinery in Texas

15: Number killed in a July 9, 1953, wildfire in the Mendocino National Forest, Calif.

Source: National Fire Protection Association and Firehouse.com