MORENO VALLEY (CBSLA) — The legal guardians of the 13-year-old boy killed after he was attacked at school said Friday they planned to sue Moreno Valley Unified School District in the boy’s death.

On Sept. 17, cell phone video showed two boys punching the victim, 13-year-old Diego Stolz, at Landmark Middle School.

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The video showed Diego being punched in the face by a boy in a black t-shirt outside the school’s main building. As he stumbles, he appears to be hit from the left by a second boy. Then, as he falls to the ground, he hits his head on a concrete pillar.

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According to students who witnessed the fight, the student was foaming at the mouth and may have suffered a seizure. Witnesses said CPR was performed on him before he was rushed to a hospital in critical condition. He passed away about a week later, on Sept. 24.

An attorney for Felipe and Juana Salcedo — the couple who had custody of Diego — said Friday that they would file a claim next week alleging wrongful death.

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The two boys accused of attacking Diego face manslaughter charges.