-- Sunday night's mass shooting in Las Vegas exposed a new vulnerability for concertgoers -- the outdoor venue.
In what is being called the deadliest shooting in modern U.S. history, at least 59 people died and 527 were injured when a gunman opened fire on the crowd at an outdoor country music concert. Officials said the gunman, whom police believe killed himself, was firing at the crowd from the 32nd floor of the nearby Mandalay Bay Resort and Casino, sending more than 22,000 country music fans scrambling for their lives.
"This guy was successful at making them into a soft target by being in a sniper position," Steve Gomez, a former LAPD officer who now works as a consultant for ABC News, told ABC News about suspected gunman Stephen Paddock, 64. "Now this has to be factored in."
Gomez said in the case of recent attacks, like the May bombing at Ariana Grande's Manchester concert or last year's shooting at an Orlando nightclub, the crowd is the attraction.
"The crowd dictates where the target is and how the attacker is going to commit the attack," he said. "If it's an open area on the street, they [the attackers] get a vehicle and crash into everybody."
In the case of outdoor concerts and festivals, where attendees are screened as they go in, the question becomes: "Is there a position up high that a bad guy can take and target that crowd?" Gomez said.
In Paddock's case, he positioned himself in "a perfect setting," Gomez said, in a hotel room high above the concert venue from where he observed the crowd for several days before attacking.
Officials found multiple weapons in the hotel room with him. "He was very well prepared," Gomez said.
"The bad guys are preparing," John Matthews, executive director of the Community Safety Institute, a public safety consulting organization, told ABC News. "We've got to do a better job of preparing our citizens."
In the case of the Vegas shooting, Matthews said there were two things concertgoers had to be concerned with -- the shooter and the crowd stampeding in the chaos.
He said one of the best things for people to do in that situation is take cover from both the shooter and the crowd. "Get under a tent, get behind something," he said. "Your chances of survival go up dramatically. Get behind a fixed structure and let the crowd go around you."
Both Matthews and Gomez stress the importance of people recognizing that being in a crowd makes them more vulnerable and thinking through what they would do in the case of an emergency.
"I tell people, be prepared, don't be paranoid," Matthews said. "When I walk into an event, I know where the main entrance is and I look for other exits. I'm looking for structures I can hide behind. It's not a matter of being paranoid but putting yourself in the best position."
It also means staying alert throughout the event.
Gomez said it's no accident that Orlando's Pulse nightclub shooting, the bombing at the Grande concert and Sunday night's mass shooting all took place at the end of the events.
"People are tired, most people are getting ready to leave, they are not thinking about what's next," he said.
As for making venues more secure, Gomez said it's nearly impossible not to mention undesirable to completely lock down a place. But Sunday's shooting showed there is still more than can be done, certainly when it comes to outdoor venues.
With more outdoor music festivals set to take place this weekend and in the future, Gomez said it's going to be important for new security assessments to take place to determine "where are the security vulnerabilities," including the most recent one exposed by the Las Vegas shooting.