During a handball game last week at Saint Anthony’s High School in Long Island, N.Y., two seniors entered the gym — one with a Confederate flag over his shoulders.

“The African-American students who immediately saw it really exercised heroic restraint, and fortunately a teacher immediately confiscated the flag and took the students out of the gym,” Brother Gary Cregan, principal of the South Huntington school, told CBS New York. He said he sees the flag as a symbol of racism.

Cregan sent a letter home to parents two days later, on Friday, saying, “This symbol, namely, the Confederate flag, carries a message that most, if not all Americans, view clearly as a reminder of a painful past where our country went to war, resulting in over 600,000 killed and, thank God, the end of slavery.”

Friday night, two sophomores took to social media — one reportedly using offensive racial language and the other posting a picture of herself wearing blackface.

Cregan told Newsday he expelled two senior boys and two sophomore girls. He had suspended the boys for 10 days, but decided stronger action was needed.

The school released a statement Wednesday, stating in part:

Saint Anthony’s is committed to addressing the issue of racial intolerance with faculty, students and parents through education, awareness and dialogue in an ongoing basis. The use of any symbol, either historic or current, which carries a meaning designed to revive past injustices, or to inflame discrimination or racial intolerance is completely unacceptable and profoundly offensive. As a Catholic and Franciscan school, Saint Anthony’s will always demand acceptance and respect for all races, religions and cultures.

The New York Civil Liberties Union (NYCLU) told CBS New York that people should be able to express their views — even those that are offensive.

“Our motto is more speech, not censorship or punishment,” NYCLU director Donna Lieberman said. “Helping children understand the impact of this patently offensive expressive activity.”

Cregan said there are limits.

“I certainly think this particular symbol of hate falls in the category of something that should be excised from our culture,” he said.