Published: Aug 28, 2014 4:28 PM EDT

NEW YORK, N.Y. - Two police officials say Joan Rivers has been rushed in cardiac arrest from a doctor's office to a New York City hospital.
    
The comedian's condition wasn't immediately known.
    
The officials spoke on the condition of anonymity because they weren't authorized to publicly name the person transported to Mount Sinai Hospital just after 9:30 a.m. Thursday.
    
Fire and police officials say they responded to a call of an 81-year-old woman having a heart attack at an upper East Side doctor's office.
    
A hospital spokesman declined to comment.
    
Rivers' representatives didn't immediately respond to requests for comment.