World of Warcraft’s big day is coming under fire.

Blizzard has noted on Twitter and in its client that it is suffering a denial-of-service (DDoS) attack which is causing high latency and disconnection in its games. This includes World of Warcraft, which just had its Legion expansion launch today. The attack was likely timed to coincide with that release.

In World of Warcraft, the attack is causing many in-game actions to take longer than usual, while other players are losing their connection to the online world. It’s also creating problems in other Blizzard games, including the team-based shooter Overwatch.

Blizzard has noted that it will provide updates on its Twitter account.