The attack took place Friday at Velvet IndieGround, a Turkish record shop that was hosting the only Radiohead album release party in the entire country. It was captured on Periscope and later uploaded to YouTube.
The attackers were apparently angry that people had been listening to music and consuming alcohol during Islam's holy month of Ramadan.
No one was killed in the attack, but some people sustained injuries including a bloodied head after one fan was hit in the face with a bottle.
A witness at the event, claiming to be one of the store's owners, recounted the horrifying ordeal:
"They were determined to kill us. We were beaten by more than 20 men with pipes in their hands, beer bottles were broken on our heads. I don't even know how we made it out. I will share the details later guys, just hoping that no one will die."
And the incident was captured on the aforementioned video (below):
"Our hearts go out to those attacked tonight at Velvet IndieGround in Istanbul. We hope that someday we will be able to look back on such acts of violent intolerance as things of the ancient past. For now, we can only offer our fans in Istanbul our love and support."