This time, the horrific act of terror struck right at the heart of mainstream American pop culture.

Does it get any more red, white, and blue than a country music festival right in the middle of the Las Vegas Strip? The killing spree of 64-year-old gunman Stephen Paddock as country star Jason Aldean performed at the Route 91 Harvest Festival on Sunday night that has left at least 58 dead goes straight to the top of the list of the deadliest mass shootings in modern U.S. history.

In America and around the world, music venues and dance clubs have become  common "soft targets" for terror. The intent to spread fear itself can be frighteningly effective as public spaces we want to believe are safe — and where we go to revel in belonging to a community bigger than ourselves — turn out to be staging grounds for horrors that really can happen here, not just in faraway places on the news.

An alarm of fear went off this spring when 22 were killed at an Ariana Grande show in Manchester, England, with that bloodshed all the more heartbreaking because so many of Grande's fans were young girls, whose joy of their first concert experience was spoiled in the worst way imaginable.

And that tragedy came after a series of other shootings that targeted crowds where music was the social glue: 89 killed at an Eagles of Death Metal show at the Bataclan theater in Paris in 2015; 39 at a disco in Istanbul last New Year's Eve. And, of course, the killer who murdered 49 at an Orlando gay dance club in June 2016, previously the worst such shooting ever in the United States.

Until Sunday. When Paddock opened fire on the crowd during Aldean's set, there were at first a few quick bursts that festival attendees thought might be fireworks, which have become almost de rigeur stagecraft at outdoor, outsized shows. By some accounts, that delayed the reaction time to the reality of what was unfolding, perhaps costing more lives.

But pretty soon it became clear what was going on, according to country singer Jake Owen, who played before Aldean and who was on stage watching the headliner when the shooting began.

"Next thing you know," Owen told CNN, "it was just unloading, like no doubt an automatic-sounding rifle or some sort of machine gun. … And that point was when you could tell that the chaos and the fear in everyone's eyes and their demeanor was changed and everyone just started scrambling for any sort of cover."

Security has grown tighter at big concert events in recent years, with fans accustomed to being scanned with a wand and walking through metal detectors. When I park my car close to Lincoln Financial Field for a big show like Metallica or U2 or Taylor Swift, I'm thankful to be met by bomb-sniffing dogs and uniformed professionals asking me to pop the trunk. And it's a certainty that there are all sorts of measures being taken to ensure safety that are invisible to most music fans.

But in the last two decades, the concert business has moved outdoors, as the festival model has grown in popularity, in summer months in regions like the Philadelphia area, and year-round in warm-weather parts of the country. A lot of those gatherings happen in big, fenced-off fields in nonurban locales. But some, like Harvest and the Made in America festival that takes over the Ben Franklin Parkway in Philadelphia on Labor Day weekend every year, take place in city centers where the main stages are surrounded by tall buildings.

Owen's description of the scene makes the vulnerability of the 30,000 fans watching cowboy-hatted star Aldean — a leading figure in the brand of celebratory pop-leaning escapism known as "bro-country" — perform on the final evening of the three-day Harvest fest clear and stark. Particularly for a sniper with an automatic weapon.

What can you do to stop that? It's hard to imagine a solution so long as mass murderers have access to weaponry that enables them to strafe a crowd with hundreds of rounds of deadly fire.

"In the way it was set up where the guy was in Mandalay, it was like shooting fish in a barrel from where he was," Owen told the cable network, saying the carnage went on "for at least 10 minutes" while he and his bandmates lay on the floor of their tour bus, waiting for the shooting to stop.

"I hate to say that, to use that kind of term, but I feel so bad for these people. … There were so many innocent people that were here to have a great time and that's what we're here to do for them, and they lost their lives."

A mass killing at an open-air music festival in the nation's most glitzy get-rich-quick tourist destination. Vegas hosted nearly 43 million visitors in 2016: That's an American horror story if there ever was one. And just as it's sure to ignite a fresh round of shouting and frustration in the gun-control debate, it's also certain to introduce a new fear for concertgoers to try to banish from their minds as they go out hoping to leave their troubles behind.