The event planned for Revolution Square, a prominent location that is home to government ministries and is often used for Communist Party events, aimed to allow ordinary Cubans to step up to a public microphone to share briefly their views on the future of Cuba.

Scheduled for 3 PM local time, it never took place. The event’s organizer, performance artist Tania Bruguera, was reported to be missing, and 14ymedio named several others said to have been detained.

In a statement posted on Facebook, Bruguera’s sister, Deborah, said Tania was taken from her home at 10 AM, after security agents banged on her door for hours. She was not allowed to be accompanied by a lawyer, and was believed to have been taken to intelligence headquarters.