Google calendar is experiencing service disruption morning of 6/30/16. Problem fully resolved at 2:36pm.
Google Apps Status Dashboard enables users and businesses to monitor the status of individual Google Apps services. Users of Google Apps can now view the status of individual services such as Gmail, Google Calendar, Google Talk, Google Docs, Google Sites and Google Video for businesses. Administrators of Google Apps Premier Edition, Standard Edition, Partner and Education Edition can also view status of the Admin Control Panel.