Within moments of Saturday’s shooting at the Melbourne Square mall, dozens of officers from surrounding agencies pulled into the parking lot, helping shoppers and locking down the commercial structure while specially trained SWAT team members prepared to do a search inside.…

Brevard Sheriff Wayne Ivey said that training and experience from other agencies shows that in such cases, citizens who find themselves confined in a building or an area with a shooter, like the dozens of shoppers and workers in the mall when the shooting happened, often have three options.

“They can run, hide or fight,” said Ivey.

—Florida Today, January 18, 2015

Even if the attacker has a gun and you do not have a weapon, the situation is not hopeless. There have been many active shooter incidents where people on the scene were able to subdue the attacker and save their own lives. We teach civilians to swarm the shooter and use other tactics, such as positioning themselves near the door but out of sight, so they can try to take the gun away from the shooter as soon as he enters.

The effectiveness of these principles was demonstrated in our analysis of the Virginia Tech active shooter event of 2007. In that incident, the shooter attacked or attempted to attack five classrooms. The people in each classroom responded in different ways. In the room that was attacked first and where no defensive actions were taken, 92 percent of the people were shot. In another room, where students had time to push a large desk against the door and hold it there, the shooter fired through the door, but no one was shot.

—Professor Pete Blair, Texas State University, from The Police Response to Active Shooter Incidents, published by the Police Executive Research Forum, March 2014

If your enemy is secure at all points, be prepared for him. If he is in superior strength, evade him. If your opponent is temperamental, seek to irritate him. Pretend to be weak, that he may grow arrogant. If he is taking his ease, give him no rest. If his forces are united, separate them. Attack him where he is unprepared, appear where you are not expected.

—Sun Tzu (fifth century B.C. Chinese general, military strategist, and philosopher), The Art of War