According to British newspaper The Sun, the star fell while reaching for things in her armoire. The accident happened in her Hollywood Hills home.
According to initial reports, the boyfriend of the actress, singer Justin Timberlake, found Diaz unconcious on her bedroom floor, and her head was bleeding. She was taken to a hospital emergency room, where she received 19 stitches and was examined for a back injury.
The paper quotes a friend of the couple as saying: "Justin was frantic with worry. Cameron was out cold and covered in blood from her head wound."
The couple had just returned from a camping vacation in South Africa. Apparently the actress was putting her camping items away when she fell.