The organization that oversees high school football in California tells TMZ Sports the Oakland high school that allowed Marshawn Lynch to participate in a full-contact practice violated state rules.
Lynch posted the video himself -- showing the 31-year-old NFL running back running over and being tackled by members of the OTHS football team during a Wednesday practice.
The problem ... the school isn't allowed to let grown men who aren't students hit (or get hit by) students.
The California Interscholastic Federation (CIF) official pointed us to this rule:
"Only 9th through 12th grade students may practice with or compete on a high school team.