Comedian Joan Rivers has been rushed to New York City's Mount Sinai hospital in critical condition.
TMZ reports that the 81-year-old Rivers stopped breathing during a surgery on her vocal chords. At one point during the process, Rivers' heart stopped beating; it's currently unclear whether doctors were able to revive her.
Daughter Melissa, who routinely appeared alongside her mother in red-carpet interviews, is reportedly on her way to New York City.
UPDATE 12:51 p.m.: E! News reports that Rivers is now in "stable condition."