BOSTON — An ugly thing happened at a high school basketball game in a suburb of Boston Friday night.

It occurred at a division title game between the all-boys Catholic Memorial School and the public Newton North High School, which has a large Jewish community of students. The game was held at Newton South High School, where an estimated 100 young men sitting in the student section cheering for Catholic Memorial shouted, “You killed Jesus, you killed Jesus,” according to several witnesses who asked not to be identified. Most of those chanting fans wore red shirts as a display of support for their team. Some of the witnesses, who were Jewish, said they found the chant alarming.

Brendan C. Hall, high school sports editor for ESPNBoston, and some other people tweeted about what happened:

“Sausage fest” — the phrase used in a chant by Newton fans — is a crude reference to the fact that the Catholic school is only for boys. Newton North, a public high school with more than 1,700 students, is in an affluent suburb just west of Boston; Catholic Memorial, the Christian Brothers School of Boston, is a college-preparatory school for boys in grades 7 through 12 about six miles away in West Roxbury, a neighborhood of Boston that borders Newton. The school’s website says that it “transforms boys’ lives and prepares them for college and the world.”

One spectator who was shaken by the events — and who asked not to be identified — is a native of Skokie, Ill., where in the mid-1970s, a controversy erupted when neo-Nazis wanted to march through the heavily Jewish town. Skokie officials tried to stop it but lost the case in court. This spectator, whose parents are survivors of World War II concentration camps, said, “I can’t believe it,” she said. “I just can’t believe it.”

Peter F. Folan, president of Catholic Memorial, released a statement Saturday:

Catholic Memorial School is deeply disturbed by the behavior of a group of student spectators who made an unacceptable chant Friday night while playing Newton North High School.

CM faculty and staff acted immediately to stop the behavior. Administrators from both schools and representatives from the MIAA discussed the incident. At the conclusion of the game, CM students were reprimanded and each student personally apologized to the Principal of Newton North High School and shook his hand before leaving the arena.

We have been the subject of hurtful chants as well and we will work diligently within our own community and with other schools to end this abhorrent behavior. Catholic Memorial School believes deeply that intolerance, of any kind, is unacceptable. We apologize for the actions of our students and we will continue to strenuously address this issue within our community.

Robert Trestan, the Anti-Defamation League’s New England regional director, said that he has been in touch with the parties involved and takes the issue seriously.

“We are very concerned why some fans thought this chant was appropriate for a high school basketball game,” Trestan said in a statement. “Hate speech has no place in the stands of any sporting event. We are grateful for the quick intervention by school officials and hope they use this as a teachable moment.”

This week Cardinal Seán Patrick O’Malley, the Catholic archbishop of Boston, gave a speech to representatives of the Jewish community to mark the 50th anniversary of Nostra Aetate, the 1965 document that revolutionized Catholic-Jewish relations and made clear for the first time that the Catholic Church rejects any form of anti-Semitism.

The two schools’ basketball teams were evenly matched going into the playoff game; Newton North was 22-3 and Catholic Memorial was 21-2.According to ESPNBoston.com, Catholic Memorial won Friday night’s game, 77-73, to advance to the EMass Final, scheduled for Monday at TD Garden, where the Boston Celtics play.

[This article has been updated.]