A screenshot circulating on social media shows an individual holding the poster that says, "ur dad is my GARDENER."
In a statement provided to Eyewitness News, the school district said it was recently made aware of the poster, which was created by students at Yorba Linda High School without the knowledge or approval of school staff.
"A picture of an individual holding the poster in question is now circulating on social media; however, the physical poster was never shared publicly on campus," a statement from the school district said in part.
"School officials are currently investigating the incident in accordance with the district's established procedures and code of conduct," the statement said. "Per Education Code, matters related to student discipline are confidential; therefore, additional information will not be shared."
Esperanza High School's football team is scheduled to play Yorba Linda Friday.
The student population at Esperanza High for the 2020-2021 school year is about 44% White and 37% Hispanic, according to the school's website.
"Unequivocally, the Placentia-Yorba Linda Unified School District condemns any and all forms of discrimination," the district said. "The district will not tolerate this kind of damaging behavior by our students or on our school campuses."
The district said students impacted by the incident will be offered mental health services.