Singer-songwriter Sia is known for accompanying her hit songs with unique music videos that tell a story.
The first scene of the video shows Maddie Ziegler, who has starred in four other Sia music videos, with rainbow-painted cheeks in place of tears.
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"I'm free to be the greatest, I'm alive; I'm free to be the greatest here tonight, the greatest, the greatest, the greatest alive, the greatest, the greatest alive," Sia sings.
"Don't give up, I won't give up; don't give up, no, no, no," Sia sings.
The dancing children all fall at once to reveal bullet holes in a wall behind them. Other rooms are shown with fallen children.
Though Sia hasn't spoken publicly about the video, Matt Moseley, a dancer who appears in the video, posted on Instagram, saying: "49 beautiful lives lost. This is for you."