PETALUMA, Calif. (AP) — Petaluma High School valedictorian Lulabel Seitz never had a chance to drop the mic at her graduation address. School officials silenced the sound system after she veered off a preapproved speech.

Seitz said later that she was "unfairly cut off" for trying to address the silencing of victims of sexual assault, something she said she experienced on the campus.

Many of the graduates wearing purple and white robes stood up, cheered and chanted "let her speak" as she tried to finish her speech June 2, The Press Democrat of Santa Rosa reported . Students clapped in support and shouted as she returned to her seat in the front row during the ceremony on the school football field.

Seitz said she was "appalled" that the school had pulled the plug on her address, though officials said all speakers had been warned the microphone would be muted if they went off message.

Principal David Stirrat said the school had been tipped off in advance that Seitz might deviate from her approved remarks.

Seitz said the school administration feared the truth. She posted video on YouTube of her interrupted speech and added an uncensored version of the full speech she tried to deliver.

In the expanded version, she said students hadn't let it drag them down when some on campus defended perpetrators of sexual violence and silenced their victims.

Seitz said she was sexually assaulted on campus by someone she knew and wanted to show frustration for a lack of action by the school.

"I thought this is a public school with freedom of speech," she told the newspaper. "This is for my class that stood up and said 'let her speak.' Even if the administration doesn't give me a mic, I still want to speak."

Seitz, 17, whose grandparents immigrated from the Philippines, is the first member of her family to graduate from high school. She will attend Stanford University.

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Information from: The Santa Rosa Press Democrat, http://www.pressdemocrat.com