ITS is aware of an outage that occurred at Google affecting Gmail. Service seems to have been restored. If the service becomes unavailable again, please refer to the Google Apps Dashboard to check status here. Google will post a report of the cause of the outage once it has been determined at the Google Apps Dashboard site.
UPDATE 2014-01-26:
Google has provided an update as to the cause and resolution of the outage. More info here:
http://googleblog.blogspot.com/2014/01/todays-outage-for-several-google.html