What to do during an active shooter situation

At least 59 people died and more than 500 others were injured when a gunman perched on the 32nd floor of a Las Vegas hotel rained down bullets on about 22,000 people attending an outdoor music festival.

As the shots rang out, some people initially paused, thinking the gunfire was actually the sound of firecrackers. Others took cover or ran, jumping over fences in an effort to flee the tragedy.

Here’s a look at experts’ advice on how best to deal with an active shooter situation.

What are the steps to take when there’s an active shooter?

In the event of an active shooter, the Advanced Law Enforcement Rapid Response Training Center says to avoid, deny and defend -- in that order, if possible.

First, Dr. Peter Blair, the executive director of ALERRT and a criminal justice professor at Texas State University, said people should avoid the attacker by creating an exit plan and moving away from the threat quickly.

The next option, Blair said, is to deny the shooter access to one’s location. That could include putting up barriers to block the shooter or turning off the lights.

And finally, as a last resort, one should defend against the attacker, Blair said. “Do not fight fairly. This is about survival,” ALERRT’s website said.

Blair told Fox News that it’s important for people to be prepared and have a “script” in mind for high-pressure situations.

"The immediate goal should be: how do I become a harder target?"

- Greg Crane, founder and CEO of the Alice Training Institute

23 FIREARMS FOUND IN MANDALAY BAY HOTEL ROOM OCCUPIED BY LAS VEGAS GUNMAN

“When you walk into any location, locate the secondary exits,” Blair suggested. “Be aware so that you can avoid the crowds all leaving out the same main exit.”

Blair also encouraged people not to take lightly the feeling that something is wrong. For example, “if the concert music stops, start taking action,” Blair said.

What if the shooter is at a higher level?

Blair recognized there could be situations when not all of the three recommended steps are viable options, such as during the Las Vegas massacre on Sunday. In instances when the shooter is at an elevated level, the only option people have is to avoid, Blair said.

In situations like Sunday's shooting, Alice Training Institute founder and CEO Greg Crane said people need to evacuate and make themselves less of a target.

WHAT WE KNOW ABOUT THE LAS VEGAS GUNMAN’S COMPANION

“The immediate goal should be: how do I become a harder target,” Crane said.  For a shooter on a higher level, that could mean standing straight up instead of lying flat on the ground, Crane said.

Anything else to know?

When the police arrive, the University of Miami’s Miller School of Medicine encourages people to make sure hands are empty and visible. People should also follow officials’ instructions and avoid making quick movements.

Blair and Crane stressed the importance of recognizing the sound of gunshots.

“If you hear repeated loud banging, treat it as if it’s gunfire,” Blair said.

Kaitlyn Schallhorn is a Reporter for Fox News. Follow her on Twitter @K_Schallhorn.