U.S. cable channel HBO said on Monday that hackers had stolen upcoming programming, and other reports claim that the theft included a script for an unaired episode of the hit fantasy show "Game of Thrones."

HBO declined to comment on the specific programming stolen in the hack. The company says that it is working with law enforcement and cybersecurity firms.

"As most of you have probably heard by now, there has been a cyber incident directed at the company which has resulted in some stolen proprietary information, including some of our programming," HBO Chairman Richard Plepler wrote in a message to employees, which the company shared with reporters.

Entertainment Weekly reported that hackers stole 1.5 terabytes of data and had already posted online unbroadcast episodes of "Ballers" and "Room 104," along with "a script or treatment" for next week's episode of "Game of Thrones."

Hacking Hollywood can have significant repercussions. Sony struggled in the aftermath of its huge hack in 2014, which leaked employee emails as well as films.

In April, a hacker claimed to have released episodes of Netflix's "Orange is the New Black" before their release by the streaming site.