It's a scenario no one wants to imagine: you're in a crowd of people when gunshots ring out, as they did Sunday night at a country music concert in Las Vegas.
Active shooter situations are usually over within 10 to 15 minutes, according to the Department of Homeland Security, and public safety experts say following a few basic principles whenever you go to a public event could save your life:
Pay attention to your surroundings
Personal safety consultant Doug Cummings says developing situational awareness - and not being oblivious to the scene around you - is key to staying safe.
"One of the key things about being aware is that it gives you a couple of minutes of extra time, sometimes to be able to flee or take some kind of an action," Cummings said.
He says many times when people are not paying attention they end up panicking, which can put them in even more danger.
Preparation is key
Whenever entering a crowded situation, experts say it's important to take note of the nearest exits, any possible dangers and places you could run to for shelter. After noting where the exits are, work out an escape route and plan in case the worst should happen.
Trying to keep distance between you and the people around you can also provide enough space to move around and see if any situations are occurring around you. Cummings said keeping people at least an arm's length away is ideal.
When shots break out
According to a guide on how to respond to an active shooter by the Department of Homeland Security, it's important to quickly determine the most reasonable way to protect your own life.
Generally, the priorities according to their guide are: evacuate, hide out, take action. Evacuation is the top priority, and everything should be left behind if it's possible to leave the area. If evacuation is not possible, then hiding out somewhere that is out of view, protected, and secured can work. Only as a last resort should the shooter be confronted, according to the guide.
If you see something, say something
Another mantra to keep in mind: if you see something, say something.
Officials with the Cook County Department of Homeland Security say while it’s nearly impossible to prevent situations like Las Vegas, many times officials learn after the fact that there were clues or suspicious behavior people noticed but didn’t report.
"What we need people to do is get over that fear of reporting suspicious activity because they could be preventing the next tragedy," said Natalia Derevanny, Cook County Homeland Security and Emergency.
Doug Cummings is the author of Escaping the 'O' Zone, which is available as an e-book