The search for Thomas Gibson's replacement for "Criminal Minds" season 12 officially begins.

TVLine revealed that CBS is looking for actors to fill the roles of two new series regulars after Gibson was fired from the long-running series over a physical altercation on the set.

According to the report, one of the upcoming characters will serve as the replacement for Gibson's character, BAU Unit chief Aaron Hotchner. However, details about the other character are still under wraps.

Gibson's unexpected departure from the show happened after he reportedly kicked writer-producer Virgil Williams in the shin in the middle of an on-set argument while filming one of the episodes for season 12. The incident was reportedly witnessed by some of the producers of the show, including showrunner Erica Messer.

Reports claimed that the incident was not a first for Gibson; he also reportedly shoved an assistant director years ago.

"Thomas Gibson has been dismissed from Criminal Minds," CBS and ABC Studios said in a joint statemen,t as reported by THR. "Creative details for how the character's exit will be addressed in the show will be announced at a later date."

But the actor has reportedly hired a top law firm in Los Angeles to file possible legal claims against the producers of the show.

According to The Hollywood Reporter, famous entertainment litigator Skip Miller and his partner Sasha Frid were hired to represent Gibson in his case.

While the search for the replacement for Gibson and the other new character is still taking place, earlier reports mentioned that "CSI: Miami" star Adam Rodriguez had been cast in a regular role as new BAU agent Luke Alvez, while Asha Tyler was promoted to series regular as she reprises her role as Dr. Tara Lewis. Paget Brewster will also return in a multi-episode arc in the upcoming season.

CBS will air the premiere episode of "Criminal Minds" season 12 on Sept. 28.