Los Angeles education officials have launched an investigation after a student showed up to school dressed as a Ku Klux Klan member.

Students at Harbor Teacher Preparation Academy in Los Angeles expressed alarm after one of their classmates arrived in white robes and a hood for a final history class project exploring racism, particularly since they said their teacher likely knew of the plan.

While other students also dressed as historical figures, the student’s decision to portray former Ku Klux Klan leader Hiram Wesley Evans - and the teacher allowing it to happen - rattled the school.

“It made me feel, like, unsafe and threatened,” senior Eliza Dumag told ABC 7.

Students said the teacher vetted and approved their proposals for topics and accompanying costumes, and some expressed bewilderment that the teacher would permit a symbol of bigotry.

“I am honestly questioning why she would think it was OK. I mean sure, he was a historical figure, but is that really a historical figure you want roaming around the school?” Dumag said

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The Los Angeles Unified School District said in a statement that it was investigating the incident, apologising and calling the costume “insensitive and highly inappropriate”.

“LA Unified and Harbor Teacher Preparation Academy understand the extreme sensitivity around this issue and do not condone or support this type of re-enactment”, the statement said. “The District and the school are committed to supporting diversity and fostering an environment to encourage student success.“