October 6, 2014 11:06 AM EDT

About 50 audience members interrupted the St. Louis Symphony’s performance Saturday night to sing a requiem for Michael Brown, the unarmed black teenager whose killing sparked weeks of often protests in Ferguson, Mo.

As the orchestra was about to play the second act of German Requiem following intermission, a man stood up in the audience and sang, “What side are you on, friend, what side are you on?” according to the St. Louis American. He was soon joined by dozens of the audience members for the second refrain, “justice for Mike Brown is justices for us all.” The demonstrators repeated the verses over and over again, you can watch the video (shot by St. Louis American reporter Rebecca Rivas) above.

Demonstrators in the balconies hung banners that said “‘Requiem for Mike Brown, 1996-2014” and “Racism lives here.” After a few minutes of singing, they started chanting “black lives matter” as they left the theater. The demonstration was organized by Sarah Griesbach, a 42-year old white woman who has been protesting against racial inequalities in the St. Louis area since Brown’s death in early August.

[St. Louis American]

Write to Charlotte Alter at charlotte.alter@time.com.

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