Update: For video of the performance, click here.
Thousands were expected and thousands turned out to sing Zach Sobiech's song "Clouds" at the Mall of America on Thursday evening.
Mall officials estimated 7,200 people filled the rotunda, joining together to sing in memory of Zach and to show support for thousands of children battling cancer.
Sobiech was diagnosed with osteosarcoma – a rare bone cancer – at the age of 14. It's a disease that strikes about 400 children and adolescents each year in the United States.
According to the Pioneer Press, boys have a 20 percent greater risk of getting the tumors, which develop in rapidly growing bones.
Zach passed away 18 months ago at the age of 18, but before he died he wrote the song about facing death as a message of hope and the song quickly went viral.
According to KSTP, Thursday's event at the Mall of America was part of the KS95 for Kids Radiothon, which benefits KS95 for Kids, Gillette Children's Specialty Healthcare and Children's Cancer Research Fund.
Other performers included Sounds of Blackness and Sammy Brown.
KS95 also held the event last year at the mall, here is the video from that event.
Proceeds from "Clouds" sales are going to the Zach Sobiech Osteosarcoma Research Fund, which has raised more than $900,000 to date.
The Sobiech family told the Pioneer Press recently they hope tonight's event will help push the fund over the $1 million mark.