Casting has already begun on season 4 of American Horror Story, despite season 3's Coven still being in production.

American Horror Story has been renewed for season 4, allowing co-creator Ryan Murphy and company to produce another self-contained installment. Murphy recently told Entertainment Weekly that many members of the Coven cast may be coming back for season 4.

"I invite people when we have a character for them. People should never read into that just because some of your favorites haven't been announced doesn't mean anything," Murphy explained. "It's a slow build and I keep adding on."

Among returning cast members, Murphy listed Jessica Lange, Sarah Paulson, Evan Peters, Frances Conroy, Kathy Bates and Angela Bassett as people he wants to work with again for season 4. Enstars previously reported that season 4 would be Lange's last season on American Horror Story.

Murphy also listed actor Finn Wittrock as someone who could come on for season 4. The actor, who worked with Murphy on The Normal Heart, has not appeared on the show before.

Reese Witherspoon Joining American Horror Story? 

As for the concept of season 4, evidence is pointing towards a carnival/circus theme. Murphy previously stated that the new location will either be Santa Fe or New Orleans, and that it would not be contemporary.

Additionally, Lange's character Fiona said the phrase "Life is a carnival," in the latest episode of Coven, which could be a hint at the new concept. Read Enstars' report on the potential concept here.

American Horror Story: Coven Spoilers: Next Episode Features Death of Major Characters? 

American Horror Story airs Wednesdays at 10 p.m. on FX.

Watch a trailer for the next episode of American Horror Story: Coven here:

Tags: American Horror Story American Horror Story: Coven Spoilers