This event was a massacre in a Chicago warehouse on February 14, 1929. 3 gangsters dressed as cops executed members of their rival gang.
This decision was taken by Al Capone to destroy his rival gang and to fully control the illegal alcohol trade in Chicago.
It was the Prohibition era so this illegal alcohol trade was making huge profits for the gangs.
Al Capone’s rivals were lured into the trap by a large shipment of alcohol. Then two ‘police cars’ pulled up outside the warehouse. As soon as one who looked like the leader of the rival gang walked in, then Al Capone’s men dressed as police entered the warehouse and killed 7 of them. Eventually the leader of the rival gang was spared after he did not enter the warehouse himself.
[Source: en.wikipedia.org]
