A student assembly on Wednesday at Washington’s Sidwell Friends School, one of the nation’s top prep schools, turned into a frightening example of hate’s pervasive reach when unidentified students projected swastikas and racist usernames on a screen in a meeting room.

Around 500 students from the ninth through 12th grades had gathered in a special meeting room in the Quaker school, which has educated Malia Obama, Chelsea Clinton and generations of Washington’s liberal elite, to listen to a student talk about an outreach organization he’d founded. The student’s group, OnSide, uses soccer to build community among refugees in the Washington area.

At the end of the program, the presenter invited audience members to use their cellphones to log into Kahoot, a game-based learning platform, to play a trivia contest in which their answers to multiple-choice questions were projected in real time on the screen. Kahoot lets participants choose their usernames, and a few students picked usernames that were racist toward Asians and Native Americans, according to an email the head of the school sent to parents Wednesday night.

Two students put images of swastikas in their usernames.

As audience members logged in to play, hundreds of usernames appeared on the screen.

“Nobody saw the swastikas at first,” one senior who participated in the game told HuffPost on Wednesday night.

But that soon changed. Kahoot awards points for accuracy and speed, pushing the best respondents to the top of a leaderboard. After two questions, a username consisting only of two swastikas shot into first place after successfully answering a question about immigration.

“It was big on the screen,” the senior said. “Everyone went quiet. ... A swastika is not something that you have in your emojis on your phone. You have to go out of your way to search for a GIF or something, copy it and paste it into Kahoot.”

A school administrator immediately signaled the presenter to turn off the projector and end the presentation. That evening, Bryan Garman, the head of the school, sent an email to parents and guardians of the students.

“We are deeply disheartened and disturbed by this incident, which is an extremely serious breach of our School’s honor code and harassment policy,” Garman wrote. “There is no place for hate in our community, and I will address the Upper School about the seriousness of the matter tomorrow morning.”