HOLLYWOOD: The sudden death of American actress Brittany Murphy "appears to be natural", the Los Angeles County Coroner says.

Tributes are flowing for the actress, who died of a heart attack earlier today, aged 32.

The Los Angeles Times said Murphy, who starred in such films as 8 Mile and Just Married, was pronounced dead at Cedars-Sinai Medical Centre after going into cardiac arrest.

A spokesman for the Los Angeles City Fire Department says officers responded to an emergency call at Murphy's home in West Hollywood at 8.00am (local time).

Murphy's mother, Sharon, discovered the star slumped unconscious in a shower at her home before her husband called emergency services, entertainment website TMZ.com reported.

The Los Angeles County Coroner says there are no suspicious circumstances in Murphy's death.

Assistant chief coroner Ed Winter says a post-mortem will be conducted in the next few days.

"We're conducting an investigation into the death of Brittany Murphy; it appears to be natural at this time," he said.

"She's been transported to our office. We come out, we look at everything, any prescription meds that we do take, we will have to analyse everything and go from there."

Police confirmed officers were at Murphy's home asking preliminary questions.

Her publicist declined to comment, saying the family wanted privacy.

Stars pay tribute

Murphy made her breakthrough in the 1995 feature comedy Clueless, playing a frumpy schoolgirl who gets a makeover from Alicia Silverstone's character.

Silverstone has paid tribute to her co-star, saying she hopes the actress is "at peace".

"I always felt connected to her as we shared a very special experience in our lives together," Silverstone said in a statement to People magazine.

"I feel love in my heart for her and hope she is at peace. This is truly sad."

Ashton Kutcher, Just Married co-star and former boyfriend, posted a tribute on his Twitter page.

"2day the world lost a little piece of sunshine. My deepest condolences go out 2 Brittany's family, her husband & her amazing mother Sharon," he wrote.

"See you on the other side kid."

Fortunes fade

Murphy had been reduced to starring in low-budget indie movies in recent years, most recently the thriller Across the Hall, which opened in one theatre each in New York and Los Angeles two weeks ago.

Earlier this month, reports circulated that she was fired from the movie The Caller, which is filming in Puerto Rico.

Her publicist said the split was "creative differences".

When she and her husband, British screenwriter Simon Monjack, returned to Los Angeles, he fell unconscious on the plane and was rushed to hospital.

Murphy had recently been photographed in an emaciated state at public events.

The starlet became a household name among teens in 1995 as the sidekick in Clueless who went from awkward wallflower to "snotty hottie".

Her last big movie was Sin City.

Murphy seemed destined for big things in the 1990s, thanks to roles in such films as the satires Clueless (1995) and Drop Dead Gorgeous (1999), as well as in Girl Interrupted, for which Angelina Jolie received an Oscar in 2000.

She appeared opposite Michael Douglas in the 2001 thriller Don't Say A Word, and played Eminem's love interest in the 2002 hit 8 Mile.

The following year, she co-starred with Ashton Kutcher in the romantic comedy Just Married and with Dakota Fanning in Uptown Girls. But the movies failed to generate much commercial or critical heat.

Murphy enjoyed more enduring success on the small screen, providing the voice of the vacuous Texan Luanne Platter in the cartoon series King of the Hill. She also voiced a penguin in the 2006 box office hit Happy Feet.

Murphy was born in Atlanta on November 10, 1977, and raised in New Jersey. Accompanied by her mother, she moved to Los Angeles in the early 1990s in hopes of stardom.