BEIJING, Jan. 6 (Xinhuanet) -- Johnson & Johnson heiress and American socialite Casey Johnson was found dead in a house in Los Angeles, according to news reports on Wednesday.

    Local police and firefighters were called to the house at 11:51 a.m. local time Monday and confirmed the death later. The authorities said they did not know the causes of the death.

    Autopsy and toxicology tests results are to be announced later.

    In a statement released, Johnson's family asked for privacy "during this very difficult time."

    Casey Johnson is one of the great-great-granddaughters of Robert Wood Johnson I, the co-founder of the pharmaceutical and medical company Johnson & Johnson.

    "I feel so sad right now, my heart is in pain. Just lost a longtime friend. My heart goes out to her family. R.I.P. Casey Johnson," her Hollywood friend Paris Hilton wrote on her Twitter page.

    (Agencies)