Keyla was gunned down in a mass shooting at the Gilroy Garlic Festival on July 28 along with 25-year-old Trevor Irby and 6-year-old Stephen Romero.
The Santa Clara County Coroner's report said she suffered gunshot wounds to her chest.
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The 19-year-old gunman, Santino William Legan, died of a self-inflicted gunshot wound within a minute of the shooting spree. Thirteen others were wounded.
Keyla's family held a celebration of life on Sunday, which would have been Keyla's 14th birthday.
Her family said she was excited to begin high school in just a few weeks and was always smiling, willing to talk to anybody.
Keyla will be buried in nearby Palo Alto in a private ceremony.
See more stories on the Gilroy Garlic Festival shooting.