EXCLUSIVE

5:00 AM PT (8/29) -- Melissa Rivers released a statement saying Joan is now "resting comfortably."



8:49 AM PT -- The NYPD tells us ... Joan is currently in critical condition.

﻿We're told ... at one point, Joan's heart stopped beating.

It's unclear if doctors were able to restart the comic's heart.

8:15 AM PT -- We're told an emergency call was placed to 911 at 9:39 AM ET and the caller said, "We have somebody in either cardiac or respiratory arrest."



Joan Rivers was rushed to a hospital in New York City moments ago ... after she stopped breathing during a surgery on her throat ... TMZ has learned.

We're told Rivers was undergoing the throat procedure in a clinic (specifically on her vocal cords) ... when she stopped breathing during the surgery.

Sources say 81-year-old Rivers was rushed to Mount Sinai hospital in New York.

We're told her daughter Melissa is on her way to New York.