The hacking group Lizard Squad is taking credit for unleashing a distributed denial of service (DDoS) attack Wednesday against Blizzard that prevented some customers from signing onto its site for several hours.

Blizzard tweeted Wednesday evening that it was monitoring a DDoS attack that was causing connectivity issues to its games. The company assured customers their account information was secured and only the site was being impacted.

At about the same time a tweet appeared by Lizard Squad stating “get ready” and followed by a series of tweets focused on the attack with one showing what could be a Blizzard email account.

Blizzard said it was back online about two hours later.

Lizard Squad has been tied to previous attacks on Blizzard, Xbox and Playstation