Whitney Houston was under water, apparently unconscious when found in the bath in her hotel room, according to Beverly Hills police.
The American star, 48, was apparently unconscious when staff discovered her lying in the tub in her hotel room on the fourth floor of the Beverly Hilton on Saturday.
Fire services and hotel security rushed to the suite but attempts to resuscitate the actress failed and she was pronounced dead shortly before 4pm local time.
Details of the hotel-room scene emerged amid frenzied speculation surrounding Houston's alleged use of prescription drugs.
Police said it was too early to determine whether these may have been involved in her death.
"Ms Houston was pulled from the tub by members of her staff and hotel security was promptly notified," said Beverly Hills police spokesman Lt Mark Rosen.
Earlier, Los Angeles County Coroner Ed Winter told reporters at a press conference that the investigation was waiting on toxicology reports, which could take eight weeks for the results to come back.
Whitney Houston's family and Beverly Hills Police Department would be the first to know why the singer died, the coroner told the press conference. He also said that there would be no restrictions on her family having her body, despite a security hold on the case.
The showbiz website TMZ reported that Houston died from an overdose of prescription drugs found in her room.
Medication, which included anti-anxiety drugs Xanax and Valium, mixed with alcohol, was the cause of Houston's death, the gossip website Radar Online claimed.
Houston was pronounced dead at 3:55pm local time on Saturday afternoon. She was due to perform at a pre-Grammy award party in Los Angeles last night.
Police in Los Angeles said that the soul diva and her entourage, which included friends, family and co-workers, had taken up a "fair portion" of the hotel's fourth floor.
"She was pronounced dead at the hotel and a number of people were able to identify her," Lieutenant Mark Rosen from Beverly Hills Police told the BBC.
Houston's daughter, Bobbi Kristina, was taken to hospital after the news her mother died. Paramedics said the 18-year-old's condition was not life-threatening and she has now been released.
Whitney Houston was the golden girl of the music industry at her peak in the 1980s and 1990s. She was also one of the world's best-selling artists.
Among her hits were How Will I Know, Saving All My Love for You and I Will Always Love You.
She won multiple Grammys including album and record of the year and her success carried her beyond music to movies like The Bodyguard.
But by the end of her career, drug use took its toll as her record sales plummeted and her voice became raspy and hoarse.
WHITNEY IN PICTURES