Criminal Minds - A.J. Cook Criminal Minds - A.J. Cook

A.J. Cook has thanked fans for their "kind words and support" as they launched an online petition protesting her dismissal from Criminal Minds.

"Your kind words and support have made me feel wanted and loved!" she tweeted Wednesday. "I love my castmates more then I can say, but they already know that. Thanks!!!"

Criminal Minds cuts A.J. Cook, will add new cast member

The 31-year-old, who has played Agent Jennifer "J.J." Jareau since the first season, was dropped for "creative reasons," a source close to the show told on Tuesday. She will be replaced with a new actress during the CBS drama's upcoming sixth season.As of early Wednesday afternoon, the petition has more than 12,000 signatures. The petition also objects to cast member Paget Brewster

's demotion next season. Brewster is currently in negotiations to return for a reduced number of episodes. She also took to Twitter to thank fans — and to vent her frustration."Creative Reasons" has been an Executive Bulls--- excuse for DECADES. It IS financial. AJ is a dreamboat. And yes, I am hurt, too," she tweeted. "Thanks to all the fans. From me, AJ and the cast. We love you. We will always appreciate your support. You are kind and wonderful. KISSES!!"

Check out photos from Criminal Minds

Thomas Gibson, Joe Mantegna, Shemar Moore, Matthew Gray Gubler and Kirsten Vangsness are all expected to return next season. All of them — save for Moore who does not have a Twitter account — have tweeted their support for Cook and Brewster, and have directed fans to the petition.

"To say we're all mystified and disappointed is an understatement...all the fan support is much appreciated!" Gibson tweeted. "Stay tuned..."