(CBS) — It’s become an all-too-familiar scenario: innocent victims injured or killed during a mass shooting.

What would you do — what should you do in response?

CBS 2’s Vince Gerasole reports the answer may not be what you expect.

Though still unlikely, the images aren’t as rare as they once were. In a seven-year period, the number of U.S. active shooter incidents doubled to 115.

“The old advice was to hunker down and wait for police,” Niles Police Sgt. Robert Tornabene says.

Starting with the deadly Columbine school shooting 16 years ago, law enforcement learned the wait for S.W.A.T forces could be deadly.

The encouraged response now is to run from the danger, hide in a secure place, and fight back as your last resort.

“You have to believe if survival is your first choice you may have to fight,” Tornabene says.

During the Sandy Hook shootings in 2012, the school’s principal did just that. Though she lost her own life, it may have bought time to save others.

On a train in France earlier this year, passengers bonded together, taking down an armed terrorist and saved lives.

Tornabene helps create crisis plans for schools and businesses. He says that kind of advance preparation means the difference between life and death.

As he explains, it’s “knowing in your mind this is what I am go ahead and do instead of your mind shutting down amid the confusion and shock.”

Some other things to keep in mind: When police arrive on scene, their first goal now is not to evacuate buildings or tend to the injured. Priority one is hunting down the shooter and getting control of the situation.