The deadliest U.S. workplace shootings in history

Workplace shootings are once again in the news after Tony DeFrances, a recently demoted executive of a company called ArrowStream, shot the company's CEO Steven Lavoie before turning the gun on himself and committing suicide, authorities said. The tragic shooting happened at 10:00 a.m., July 31st inside The Bank Of America building in Chicago's Loop.

This event is just another tragic addition in a sad history of workplace murders. Check out the gallery above to see murderers behind the deadliest U.S. workplace shootings.