Hackers targeting Sony Pictures Entertainment leaked up to five movies over Thanksgiving weekend and shut down the company's email temporarily. Some see the breach as a possible attack by North Korea, which is displeased by one of the studio's upcoming movies. Investigations into the leak are currently underway.

A group calling itself Guardians of the Peace, or GOP, claimed to have hacked Sony Pictures Entertainment and leaked a series of movies the studio recently released or will release soon, according to the Hollywood Reporter. Among those films now making their way through file-sharing sites are "Annie," "Fury," "Mr. Turner," "Still Alice" and "To Write Love on Her Arms."

Though "Fury" was released to cinemas in October, it has not been released on DVD yet. Someone claiming to be part of GOP emailed journalists over the weekend saying they hacked Sony and threatened the studio with releasing other information. However, the email's credibility cannot be authenticated.

According to the BBC, Sony shut down its internal system because of an "IT matter" last week. The company has yet to confirm who leaked the films.

"The theft of Sony Pictures Entertainment content is a criminal matter, and we are working closely with law enforcement to address it," a spokesperson for the company said, refusing to provide any other details.

However, there could be the possibility that North Korea is behind the cyber attack. At least, Sony is pursuing that lead, according to Re/code. Sources close to the investigation and Sony told Re/code that it is possible a third party, operating out of China, hacked the studio in North Korea's behalf.

The hacking locked out Sony employees out of their computers, and GOP threatened to disclose information stolen from servers if their demands are not met. What these demands are, we do not know.

Nonetheless, North Korea's involvement is not a stretch, as the Hermit Kingdom has denounced one of Sony's upcoming movies: "The Interview," starring James Franco and Seth Rogen.

Set to be released on Dec. 25, the comedy tells the story of how Rogen and Franco are enlisted to assassinate the North Korean leader.

Earlier this year North Korea called the film "reckless U.S. provocative insanity" and an "act of war that we will never tolerate," according to The Associated Press.

To help with the investigation, Sony hired FireEye Inc.'s Mandiant forensics unit, reports Reuters. The FBI is also investigating the matter.