Tragedy has rocked the “9-1-1: Nashville” … one of the show’s young actresses, Isabelle Tate, died shortly after filming an episode.

According to her obituary, the rising star died Sunday at age 23. Her agency, McCray Agency, confirmed the heartbreaking news … though her cause of death has not been disclosed.

Isabelle played Julie in the pilot of ABC’s newest “9-1-1” spinoff, starring LeAnn Rimes, Chris O’Donnell, and more. Before breaking into acting, she graduated from Middle Tennessee State University.

Friends and family are remembering her online as “full of fire,” “a fighter,” and “the most caring, loving person.”

She was 23.