(CNN) A group of Southern California high school students face disciplinary action after spelling out the n-word with lettered T-shirts at a senior picnic.

The Escondido Union High School District this week confirmed that about 10 students at a senior event "made a poor decision" by participating in the stunt involving the racial slur, CNN affiliate KGTV reported.

"We are a campus that prides itself on inclusion and embraces diversity," Principal Adriana Lepe-Ramirez said in a statement.

"We will not tolerate actions that send messages of racism and promote divisiveness."

The statement said Escondido High School, district officials and local police were investigating the incident, the station reported.

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