When Gwenn Cujdik heard about the Manchester bombing, she had a sickening thought:

"Oh, my God, that could have been us."

Her 10-year-old daughter, Layla, loves Ariana Grande.

When the pop superstar's tour landed in South Philadelphia in July 2015, Cujdik joyfully took Layla's hand and hustled through the doors of the Wells Fargo Center, both of them eager for the show and happy to share some mother-daughter time.

On Tuesday, the memories of that night still shiny and sharp, Cujdik was left to explain that people who went to hear the singer in England were dead on the ground, after a terrorist bombing killed 22 and injured dozens more.

Layla, her mother said, responded with a single, unanswerable question: Why?

Across the ocean, Manchester authorities worked to identify those responsible, and Queen Elizabeth II condemned an "act of barbarity" that shocked the nation.

In Philadelphia, with Wawa Welcome America coming in July and the two-day Made in America concert in September, the landscape suddenly seemed potentially dangerous. Nervous parents and promoters took stock of the carnage overseas.

At a news conference to announce details of Welcome America, event president and CEO Jeff Guaracino said Tuesday that safety and security were top of mind.

"We're constantly meeting and evaluating," he said.

Manchester Arena, where the bombing occurred, is operated by a Conshohocken-based firm, SMG, founded in the 1980s by the late Flyers owner, Ed Snider. Snider sold his interest in 1997. The company runs dozens of stadiums, theaters, and centers around the world, including the Convention Center.

The firm said in a statement that Manchester Arena management was assisting law enforcement officials in the investigation, and directed questions to that city's police department.

"Our thoughts and prayers go out to the victims and their families," the company wrote.

Parents here also were focused on the attack.

Cheryl Squadrito belongs to a live-music-loving family, routinely taking her son and daughter to concerts, everything from the Philadelphia Orchestra to the Zeppelin tribute Get the Led Out.

Now she's worried.

"I'm going to be hyper-vigilant," said Squadrito, president of Media Friendly Public Relations in Haddonfield. Her son, Matthew Moskovitz, 14, still wants to see the band Chicago perform in Camden in July. Her 13-year-old daughter, Natasha, had a question about the bombing:

"I wonder how Ariana feels?"

"I bet she feels terrible," her mother answered.

Squadrito's firm has clients overseas — she was communicating with one in England shortly after the bomb went off. Soon after that, authorities said the explosion was a terrorist attack.

Squadrito thought of all those teens and tweens, many of them probably dropped off at the show by their parents. And the horror of mothers and fathers rushing to the arena, not knowing if their child was alive.

"It's like these awful people took away these kids' innocence," she said.

For Cujdik, 39, a Philadelphia assistant district attorney, the Wells Fargo concert remains a night of magic.

Her daughter grew up watching Grande on Victorious, the  Nickelodeon show. The Wells Fargo concert, featuring Grande and Katy Perry, was such fun, with "all the kitty ears and bright colors," like "a little party."

Security, Cujdik recalled, was typical for a concert — bags were checked. Nobody expected trouble. It wasn't an Eagles-Giants game.

When she heard about the bombing, she immediately thought of that night at the show with Layla, now 10. And of the families in England.

"My first thought was there have got to be kids" hurt, Cujdik said. "I'm kind of speechless. Last night was really hard for me. It's real. The violence is real. Every time you think you can take a breath, there's the next one. And it always seems to be the worst one."