A dozen employees said they watched a “large, disc-shaped craft” hover above a Colorado concert venue and then vanish.

“What’s even crazier is that as soon as we all started noticing it and stopped what we were doing to pay attention to it, the craft tipped at an angle and slowly started moving belly-first to the east,” an employee reported to the National UFO Reporting Center about the June 5 sighting at the Red Rocks Ampitheatre in Morrison.

“Then it started fading away until it was invisible. It didn’t shoot off into the distance. It simply dissolved into the ether. We all watched it vanish.”

According to the National UFO Reporting Center, the “silent” hovering object was long—about the size of a “three-story office building”—and had three levels of windows and lights.

“One of our coworkers suddenly said to us, ‘Hey, what is that over there? It looks like a spaceship,’” the anonymous reporting employee wrote.

“We all turned to look in the direction he was pointing, and sure enough, a UFO was hovering about half a mile to a mile north of Red Rocks.”

They all turned their attention to the strange object in the sky, which suddenly “fade(d) into nothing as soon as it knew it was being watched,” according to the National UFO Reporting Center post.

That’s when it “simply dissolved into the ether.” “A dozen of us saw it. We all kept asking each other, ‘Are you seeing this too?’ It was a resounding, ‘Yes,’ from everyone in the group,” the worker wrote in the post.