PROVO, Utah (AP) — Malfunctioning fireworks veered into the stands at a crowded Utah football stadium and struck members of the audience during a Fourth of July celebration, sending up to six people to the hospital, according to authorities and the event organizer.

The mishap occurred during the opening ceremonies of the Stadium of Fire show, the flagship event at Provo’s annual Freedom Festival at Brigham Young University’s LaVell Edwards Stadium. The fireworks were shot off inside the outdoor arena as several jets passed overhead.

As many as six people were taken to the hospital, including one with serious injuries, Cook said, adding that he did not know the severity of the other injuries nor the number of people who were struck by fireworks.