The concert and event ticketing company, Ticketfly, is working to get its systems back online after a cyber-attack last week. Ticketfly has confirmed the hack but has released little information.

“Ticketfly.com has been the target of a cyber incident,” the company said in a statement posted on its website. “In consultation with leading third-party forensic and cybersecurity experts, we are in the process of bringing the Ticketfly ticketing system back online with the security of our clients and fans top of mind.”

According to news reports, hackers took control of the Ticketfly website last Wednesday and have stolen customer information. Some reports say that the hackers are still in control of the site and have demanded to be paid in Bitcoin. It’s been reported that as many as 26 million customer might be affected by the hack.

Ticketfly is owned by Eventbrite, the event technology platform.