The 32-year-old star of films such as "Clueless" and "8 Mile" died Sunday morning after collapsing at her Hollywood Hills home. Paramedics tried to revive her, but she was pronounced dead at Cedars-Sinai Medical Center.
Assistant Chief Coroner Ed Winter said they will conduct an autopsy Monday to try to determine what killed the actress, and said her death appeared to be from natural causes. He said the illness, reported to officials by her family, could have contributed to her death, but it will be weeks before a final determination is made.
Toxicology tests will be performed, and officials will contact her personal physician to get a better sense of Murphy's medical history, Winter said.
Neighbor Clare Staples said she saw firefighters working to resuscitate the actress Sunday morning. She said Murphy was on a stretcher.
Murphy's husband, wearing pajama bottoms and no shoes, appeared "dazed" as firefighters tried to save her, Staples said. "It's just tragic," she added.
Funeral arrangements have not been announced.
"The sudden loss of our beloved Brittany is a terrible tragedy," Murphy's husband and family wrote in a statement. "She was our daughter, our wife, our love, and a shining star. We ask you to respect our privacy at this difficult time."
Murphy's death put "Saturday Night Live" in an awkward spot. Two weeks ago, the NBC show aired a sketch during "Weekend Update" in which cast member Abby Elliott performed an impression of Murphy, who had recently been fired from a film project. The impression portrayed Murphy as spacey and living in the past.
After her death Sunday, the sketch disappeared from Hulu.com, the online video repository co-owned by NBC Universal.
The quiet removal prompted many bloggers and online viewers to question the sketch's tastefulness and the decision to erase it without notice. A publicist for "Saturday Night Live" didn't respond to requests for comment.
Murphy moved to Los Angeles with her mother, Sharon, in the early 1990s. Her career started with small roles in television series, commercials and movies, but her part in "Clueless" led to larger projects.
She is best known for parts in "Girl, Interrupted" and "8 Mile," and also voiced the character Luanne Platter for more 200 episodes on Fox's animated series "King of the Hill."
Her role in "8 Mile" led to more recognition, Murphy told AP in 2003. "That changed a lot," she said. "That was the difference between people knowing my first and last name as opposed to not."
She married British screenwriter Simon Monjack in 2007.
Murphy's father, Angelo Bertolotti, said he learned of her death from his son, the actress's brother, and was stunned.
"She was just an absolute doll since she was born," Bertolotti said from his Branford, Fla., home. "Her personality was always outward. Everybody loved her - people that made movies with her, people on a cruise - they all loved her. She was just a regular gal."
He said he hadn't heard much about the circumstances of Murphy's death. Bertolotti divorced her mother when Murphy was young and hadn't seen Murphy in the past few years.
"She was just talented," Bertolotti said. "And I loved her very much."
AP writer Matt Sedensky in Miami contributed to this report.