UPDATE: Microsoft has updated that all services should be working as normal.
ORIGINAL POST:
As posted by Microsoft, there is currently a widespread outage that is preventing users from authenticating to many Microsoft Services. Microsoft does believe that they have identified root cause of the issue and working to correct it at this time.
These issues are solely on Microsoft systems. For more details, please go to https://status.office.com/. We will update Network News as more information becomes available.