MARTINEZ (CBS SF) — The Martinez family of a 15-year-old high school freshman is looking for answers as to why the girl died suddenly Sunday afternoon after waking up that morning not feeling well.

Savannah Alexander died on her 15th birthday, while visiting family in Turlock in Stanislaus County for the holidays, according to Steven Bradon, Savannah’s uncle. She went to bed Saturday night feeling fine, Bradon said, but complained of a stomach ache when she woke up Sunday.

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“This happened so suddenly,” said Bradon, who lives in Fresno. He got a call from his sister Christina Alexander, Savannah’s mom, at about 1:30 p.m. Sunday saying Savannah was sick and at a Turlock hospital.

Bradon immediately left Fresno for Turlock, but didn’t get there in time to say goodbye.

“By 3 p.m. she was gone,” he said.

As of Tuesday, it is unclear why Savannah died. A spokesman for the Stanislaus County Coroner’s Office said an autopsy will be performed sometime this week.

“It’s frustrating right now … we don’t know how, we don’t know why,” Bradon said. “She was perfectly healthy, and that’s why it’s so hard for all of us right now.”

The family members in Turlock had all just received negative COVID-19 test results, he added. “We’re trying to find a little bit of closure in our lives.”

Kerry Cusack, principal at Martinez Junior High School, sent an email Monday to students and their families with the news of Savannah’s death. Savannah was a student at the junior high school last school year.

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“As the MJHS staff learned in our time with her, Savannah was a kind and friendly bright light here at MJHS,” Cusack said in the email. “She was a hard worker, loved art and was always willing to help others.”

The junior high school is offering grief counseling services via telephone Tuesday and Wednesday for students who want it, Cusack added.

Bradon said Tuesday that, as a baby, Savannah had been at his high school graduation, and at his wedding a few years ago. Savannah had a passion for taking care of animals and loved to help her younger brother Jeremiah, her only sibling, build Lego sets together. She also loved writing, and kept her diary in her backpack, and wrote in it frequently.

Bradon read one of the last entries in her diary: “My life is meaningful because, at the end of the day, I’m still human because human lives matter.”

Savannah was always smiling, Bradon said. “She had nothing but love for this world.”

Bradon set up a GoFundMe page to raise money for Savannah’s funeral expenses. As of Tuesday afternoon, the fund had collected more than $14,000 toward a goal of $20,000. Family members are seeking a gravesite in Richmond near other family members, Bradon said.

The donations not only help fulfill a monetary need, Bradon said, but an emotional one.

“That’s how I know people truly care,” he said.

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