Dressed in cropped black pants, strappy white sandals and a sparkly jacket, Disney star Peyton List stepped out to the show with her pals, Aidan Alexander and Bailee Madison. Inside the venue, the trio couldn't stop gushing over Gomez, singing along to every word.
There was also a mini High School Musical reunion, with both Ashley Tisdale and Vanessa Hudgens in attendance. Tisdale, 31, rocked a black-and-white striped dress, which she paired with over-the-knee boots and black leather cross body bag. Hudgens, 27, kept it cool in an orange jumpsuit, a long black jacket and snakeskin purse.
"Rockin out to @selenagomez with my girl @vanessahudgens," Tisdale later wrote on Instagram. "So proud of you Sel!! You're doin it!!!!"
Rockin' out, indeed! An eyewitness tells ET that the two were having a blast taking selfies from inside the Hyde Lounge at Staples, which was stocked with an open bar, hot dogs, macaroni salad and pulled pork sandwiches as part of Call It Spring's private party.
Their former Disney colleague, Joe Jonas, was there as well. The 26-year-old singer opened Gomez's show with his pop rock band, DNCE. An eyewitness saw Tisdale "dancing a ton" to their hits with her husband, Christopher French, as she waited for Gomez to take the stage.
Also spotted were Halle Berry, Tobey Maguire, Jonathan Bennett, Cody Simpson and Courteney Cox.
At one point during the show, Gomez took a moment to reflect on the recent tragedies that have shaken the world, including a mass shooting in Dallas that took the lives of five police officers, and the deaths of two men, Alton Sterling and Philando Castile, who were shot and killed by police in two separate incidents in Baton Rouge, Louisiana, and Falcon Heights, Minnesota.
"So much craziness is going on, and I think people forget. I think people forget that it's -- we're not gonna get anywhere with violence," she exclaimed. "This next song is called 'Kill Em With Kindness.'"
Gomez pulled out all the stops for her star-studded show, donning a number of glitzy performance ensembles. Other songs from her set list included "Who Says," "Same Old Love" and "Hands to Myself."
Gomez is currently traveling the country as part of her tour, but that hasn't stopped her from finding some time to relax with friends. Last weekend, Gomez celebrated the Fourth of July with her gal pals by her side -- and it appears she even played host!
To hear more on her festive party, watch the video below.