BLOOMINGTON (AP) — Thousands of people are expected to gather at the Mall of America to mark the anniversary of the debut of a song written by a Minnesota teen who died of cancer.

Zach Sobiech was 18 when he died from osteosarcoma in May. Before he died, he turned to writing music and his farewell song, “Clouds,” became a hit.

In the last year, the music video for “Clouds” has had 8.3 million views on YouTube, and the song has been No. 1 on iTunes.

On Thursday night, more than 4,000 people — including area school and church choirs — plan to gather in the Mall of America rotunda to sing “Clouds.”

The event is part of the KS95 for Kids Radiothon, benefiting Children’s Cancer Research Fund and Gillette Children’s Specialty Healthcare.