During her graduation, high school valedictorian Rooha Haghar's speech ended abruptly, just as she began to list the names of black teens who were shot by police. Haghar says the school purposefully muted her mic.

In a now-viral tweet, Haghar can be seen speaking at her graduation from Emmett J. Conrad High School in Dallas, Texas. "To Trayvon Martin, Tamir Rice and all the other children who became victims of injustice," she begins. Then, the mic cuts off.

Haghar tweeted a video of the moment. As she began her sentence, Principal Temesghen Asmerom can be seen motioning to someone offstage. Her tweet mentions that the school "played it off as a technical difficulty. [P]athetic."

my valedictorian speech was cut short because i said the names of black children who had become victims of police brutality. our principal signaled for my mic to be turned off as soon as i said “trayvon martin and tamir rice” and played it off as a technical difficulty. pathetic. pic.twitter.com/9upW3dZ7Mg — روحا (@ItsRoohaHaghar) June 3, 2019

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Haghar shared on Twitter the portion of her speech that was cut off: "To Trayvon Martin, Tamir Rice and all the other children who became victims of injustice ... To the kids across the globe affected by war, famine, persecution and child labor who have lost years of education due to hunger, displacement, lack of finances and lack of educational resources, I'm sorry."

Haghar said that when she first read the speech to one of her teachers a week before graduation, she was told to remove Martin and Rice's names from it. "I was told mentioning those names will incite anger towards which people, a group which according to him experience high levels of discrimination in America," she tweeted. "He advised me to take that line out completely. I didn't."

some more context and background information. i really think my principal did this out of ignorance, and we all have room for growth. i never meant to create more divisiveness, but i also feel like certain conversations need to be had pic.twitter.com/1YOEe8a91d — روحا (@ItsRoohaHaghar) June 4, 2019

Haghar said her principal also asked her to remove the line, telling her it does not comply with "DISD [Dallas Independent School District] valedictorian speech guidelines," which Haghar said she has never had access to. She said the principal asked her to make her statement vaguer, to not highlight black people specifically.

The deaths of Martin and Rice — both unarmed teenagers when they were shot — helped spark the Black Lives Matter movement and protests against police brutality across the country.

"I knew the risk I was taking but never expected to be silenced," Haghar tweeted.

"It is never our intent to censor anyone's freedom of speech," DISD told CBS News in a statement. "Students have that right — Dallas ISD encourages it. Our charge is to ensure the rights of all students are respected and no one's rights are infringed upon. In hindsight, we realize this decision may not have been reflective of the core values we teach our students, as we work to educate leaders of tomorrow. For that, we apologize."