Raw video:July 04/08,Charles City,Iowa:(DES MOINES, Iowa) — A Fourth of July fireworks shell misfired in a northern Iowa town, sending a fireball skidding down a street into a crowd of spectators and injuring 37 people, officials said Saturday.

Most of the people treated after the Friday night accident in Charles City suffered minor injuries, city fire department spokesman Eric Whipple said.

It appears there was a misfire involving 13 racks of firework tubes during the finale of the city-sponsored show, Assistant Fire Chief Dave Beamer said Saturday.

Officials didn't yet know why the fireworks malfunctioned, Beamer said. Inspectors from the state fire marshal's office in Des Moines visited Charles City on Saturday.

"It appears they went horizontally across the ground, some of them," Beamer said of the fireworks.