Thousands of people gathered at the Mall of America on Friday night to honor the late Zach Sobiech and children sick with cancer and other serious illnesses.

More than 5,000 had registered earlier this week for the third annual “Clouds” Choir for a Cause, in the mall’s rotunda. There, the crowd sang and recorded Sobiech's song "Clouds," as well as “Jingle Bells” as well as other Christmas songs and carols.

Sobiech died in 2013 after a four-year fight against osteosarcoma, a rare form of bone cancer. In his last months, the 18-year-old Lakeland teen turned to his guitar and wrote songs to say goodbye to those he loved.

The music video for “Clouds” has about 12.3 million views on You Tube.

New this year, Ryan, Shannon & Fish from KS95 radio unveiled the total from KS95 for Kids Radiothon, held throughout the day Friday. The effort raised at least $513,319.94 to benefit Gillette Children’s Specialty Healthcare and the Children’s Cancer Research Fund.

Sobiech first shared his music on behalf of the Children’s Cancer Research Fund at the 2012 KS95 for Kids Radiothon.

Staff writer Nicole Norfleet contributed to this report.