Hackers have broken into the networks of HBO and reportedly leaked unreleased episodes of a number of shows, as well as the script for next week’s “Game of Thrones” episode. Altogether, they have reportedly obtained a total of 1.5 terabyte of data.

HBO confirmed the intrusion in a statement sent to Variety.

“HBO recently experienced a cyber incident, which resulted in the compromise of proprietary information,” the networks said. “We immediately began investigating the incident and are working with law enforcement and outside cybersecurity firms. Data protection is a top priority at HBO, and we take seriously our responsibility to protect the data we hold.”

Entertainment Weekly was first to report about the hack, and allegedly leaked content, on Monday. According to that report, the hackers have already leaked unreleased episodes of “Ballers” and “Room 104.”

HBO chairman and CEO Richard Plepler addressed the hack in an email to employees, calling it “disruptive, unsettling, and disturbing for all of us.” Plepler said that the problem is being addressed by “senior leadership and our extraordinary technology team, along with outside experts,” and went on to call the efforts to mitigate the hack “nothing short of herculean.”

“The problem before us is unfortunately all too familiar in the world we now find ourselves a part of,” he wrote. “As has been the case with any challenge we have ever faced, I have absolutely no doubt that we will navigate our way through this successfully.”

It’s still unclear who’s behind the hack, but it’s far from the first time that Hollywood has found itself in the crosshairs of hackers. A group of hackers that is thought to have been backed by North Korea broke into the networks of Sony Pictures in 2014, and subsequently released tens of thousands of emails, as well as scripts and video files.

And in late 2016, hackers broke into the network of a small Hollywood-based post-production vendor and stole TV show episodes from Netflix and multiple other TV networks.