An autopsy on comedian Joan Rivers' body is inconclusive and more tests are needed to determine the comedian's cause of death, the New York City medical examiner's office said Friday.

"We will need to do additional investigations before we can determine that," Julie Bolcer, a spokeswoman for medical examiner's office, said.

Rivers, 81, died Thursday at Mount Sinai Hospital in Manhattan. She had gone into cardiac arrest after undergoing a routine procedure on her vocal cords at Yorkville Endoscopy. She had been hospitalized since Aug. 28.

As she wished, Rivers will have a red carpet at her funeral Sunday at Temple Emanu-El in Manhattan, and it will be buried with her, Us Weekly magazine reported Friday.

Rivers had been in a medically induced coma after she was rushed from Yorkville Endoscopy to the hospital. The New York State Health Department has said it is investigating the circumstances that led to her death after the procedure at the clinic. The clinic has not publicly commented.

Mourners gathered outside Rivers' Central Park West home Friday and left white and lavender orchids, red and pink roses, sunflowers and daisies.

One of many handwritten cards said: "Melissa & family please read." Another card said: "Dear Joan, thanks for the laughs," in pink letters.

"She had courage with a punchline," Jeff Soon, 72, of Jersey City, said in front of the home. "Her fight with Johnny Carson proved her courage."

In the 1980s, Rivers, the stand-in host for "The Tonight Show Starring Johnny Carson," went to Fox to launch a late-night show there. Carson found out late in the process and never spoke to her again.

Lovene Gowins, a housekeeper/nursing assistant in Rivers' neighborhood, stopped by Rivers' home after work.

"She was a real humanitarian here in the neighborhood" and fed the homeless, Gowins said.

"She was a real New Yorker. She never left us," Gowins said.

Frank Rosado, 55, an actor and waiter from Yorkville, remembered when Rivers starred in Neil Simon's "Broadway Bound" at the Broadhurst Theatre on Broadway in the 1980s.

He worked in a souvenir store nearby and left Rivers a card at the theater. "I'm happy to see you on Broadway," he wrote.

She came into the store to thank him; he missed her.

"She was a workaholic but she loved her job. She was one of a kind -- a real tough Jewish girl," he said.

With Maria Alvarez