It's hard to imagine what you can really do in a situation like in Las Vegas, but expert law enforcement trainers we spoke with offer a few tips that could increase your chances of survival.
In a large venue the first thing you can do is know where your exits are.
Ask yourself, if something goes horribly wrong, where can I go?
"Number one try to keep your cool" says retired FBI Agent Brian Kensel.
Kensel recognizes that's easier said than done but remaining calm can help you make good decisions when running away.
He says the obvious first choice is to get out of the "kill zone" as quickly as possible.
Experts say getting behind something like a wall can be good to hide yourself from a shooter, but it's not going to stop a bullet in some cases.
Kensel adds, "Rifle rounds of this nature will go through a cement block."
A car can be a good shield to protect yourself, but you want to get behind or under the engine block.
Kensel says hiding behind the trunk of the car or the doors may not protect you from a bullet..
"The only place in a car that is effective from ballistic protection, especially from a rifle, is the engine block."
If you're trapped with limited or no options like many were during the Vegas shooting, experts say getting down like people did is good, but you can take it a step further to increase your chances of surviving.
Ball yourself up and make yourself as small as you can.
Tampa Police Officer Sean Mahabir adds, "Make yourself small and when that opportunity comes take off. Run as fast as you can and don't look back."
Officer Mahabir teaches active shooter training courses to local businesses at no cost.
"Tampa Police Department has a program called Business Watch Tampa, and part of that program offers a free presentation in this case an active shooter presentation.
The Department of Homeland Security has a video online called "Run, Hide, Fight" with additional tips.