Everyone, from party-goers to police, felt the beat of this surprise outdoor rave.
"I'm here to see Skrillex and Fred again, like, I'm right outside City Hall. It's absolutely beautiful outside and. Yeah, why not," said SF resident Hiren Mystery.
Fans filed in late afternoon for DJs Skrillex and Fred Again.
"Skrillex is one of my favorite artists. He has been for a very long time. So it's, you know, it's been a dream to see him I'm actually really excited about it," said Justine Fibler from San Jose.
RELATED: 25,000 fans headed to San Francisco for sold out rave with Skrillex, Fred Again
Skrillex hinted at the show earlier in the week. All 25,000 tickets were sold.
"Tickets were so hard to get. It's going to be all the people that were invested into putting in the time to get them," said Dan Withers from San Francisco.
"It was like, I texted all my friends like a few days ago, and I was like, 'Are you guys down to hit this event?' at the very last second, and then we did it," said Carolyn Hanson.
And the city's counting on events like this to help bring back downtown.
"I don't think there is really that one silver bullet when it comes to revitalizing and reimagining downtown San Francisco post pandemic," said Melissa Buckminster with the Downtown SF Partnership. "But having that consistent drum and beat or exciting events and activations is definitely going to be a really big factor."
Fences up and security high, the show was shielded from the public and police presence was strong.
"I'm just excited to be here with my best friend and to experience this. And yeah, I just wish everything was perfect and safely and everybody loves each other and has a good time," said San Jose resident Cortnie Williams.
And that's exactly what this crowd did.
"The idea of doing an event in such a historical place is like nothing that's ever that I've ever been to personally. So, I get to do that, and I get to have my friends along with me. Like, there's nothing better," said Judith Martin from SF.