Emergency communication system
The 2012 Aurora shooting happened on July 20, 2012, when a gunman opened fire during a midnight showing of the movie "The Dark Knight Rises" in Aurora, Colorado in the United States.  During the attack, the gunman was not stopped.  Many of the people in the audience even thought that the action was part of the movie, as a special effect. It often happens in movie theaters that people are told to turn off their communications devices (for example cell phones); and no attempt was made to warn them this way. In this type of situation, an on-location, clear warning might have helped lessen the effects of the attack.