Twentieth Century Fox and director James Cameron announced today that the “Avatar” sequels have grown in number from two to three.

Cameron has hired screenwriters Josh Friedman (“War of the Worlds”), Rick Jaffa & Amanda Silver (“Rise of the Planets of the Apes”), and Shane Salerno (“Savages,” “Salinger”) to collaborate with him on the screenplays for “Avatar 2,” “Avatar 3” and “Avatar 4.”

The three tentpoles will be filmed simultaneously with production beginning next year. The release of the first sequel will be in December 2016, with the second to follow in December 2017 and the third a year later.

Though Friedman is best known for writing on the TV show “The Sarah Connor Chronicles,” Friedman’s attachment is just a coincidence since Cameron had nothing to do with the show even though he helped create the “Terminator” characters with Gale Anne Hurd.

Cameron is producing with his Lighthouse Entertainment partner Jon Landau. No release date has been set.

The first “Avatar” is the highest grossing film at the domestic and worldwide box office having earned more than $760 million domestically and $2.7 billion worldwide.