UPDATE: PSN service is returning to users after a brief outage.
Sony's U.S.-based PlayStation Twitter feed posted the following update after 5 p.m. on Wednesday: "PSN update: If you encountered issues logging in today, try logging in now. Apologies for the inconvenience!"
Sony's PlayStation Network went down sometime after noon on September 21.
According to a 3 p.m. tweet from PlayStation Blog EU, "Current indications are that we'll be restoring PlayStation Network services in approx. two hours. We appreciate your patience."
A tweet posted just before 3 p.m. stated that the engineers were working on a fix but did not cite the cause of the outage.
In April, Sony took the cloud-based gaming and entertainment network offline for several weeks after a security breach exposed millions of users' personal data. The incident led to scrutiny from lawmakers and created an enormous public outcry from customers around the world. The network then suffered a rash of hack attacks as it attempted to restore service and mollify users.