Ruby on Rails CAS SSO

I have a RoR API ( Rails 4.1.x ) and an ember application for the front end. At the moment I use device database_authenticatable AND I have added a third party login option by using ember-torii and ember-simple-auth modules.

I want to add an SSO mechanism with a CAS server. Is it possible to have both cas authentication AND database authentication on the same application with devise? Or could anyone suggest a clean solution for having both authentication options?