ANAHEIM ( — The mother of a 15-year-old severely autistic student claims her son was left alone on a school bus for six hours in Anaheim.

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Lucie Hoang said her son, Patrick, takes the bus to Savanna High School every week day.

On Sept. 11, the bus driver picked Patrick up, but the teenager didn’t get off the bus with the other students.

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Hoang said the driver later found her son, who is prone to seizures, sitting on the bus at the end of the school day.

Hoang said she’s tried to call the Anaheim Union High School District for weeks, but was told the incident was under investigation.

“I can forget this. But I can’t forgive myself because I’m his voice. I cannot let that happen. I can forgive the driver… but (I at least want an) explanation,” she said.

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KCAL9’s Stacey Butler said Hoang isn’t interested in a lawsuit against the school district—she just wants an apology.