Sony PlayStation's online store was unavailable for more than two hours on Monday night after hackers took down the site. Visitors were greeted by a message that read "Page not found. It's not you. It's the internet's fault."

The Japanese company is still busy restoring its servers and investigating the recent hack in Sony Pictures that prevented its employees from accessing company emails and released the DVD screener versions of upcoming movies "Fury," "Annie," "Mr. Turner," "Still Alice" and "To Write Love on her Arms."

Sony confirmed that its PlayStation network went dark between 6:52 p.m. to 9:18 p.m. ET, and that the hack has affected all of its users across the globe. The company is still investigating the cause of the network problem and does not know if any was compromised during the attack, according to Financial Times.

Meanwhile, a hacker group that calls themselves "Lizard Squad" claimed responsibility of the attack via Twitter but did not tell their reason for hacking the PlayStation network.

Sony responded on Twitter by acknowledging the problem.

Lizard Squad is the same group that hacked the PlayStation network in August, as well as Xbox Live last Friday, PC World reported.

It is still unknown if the Sony PlayStation hack is related to the Sony Pictures hack. If that were the case, North Korea might be the primary suspect again even if its government has denied the previous allegation. However, some security experts believe that the two cases are not related.

Sony's shares plummeted by 3.3 percent to $21.40 on Monday after news of the hack broke.