The accident occurred about 10:30 p.m. Friday in Charles City, the Charles City Press reported.

Mark Wicks, the newspaper's managing editor who was videotaping the fireworks display from a small plane, said he saw what seemed to be a large but very short-lived ball of fire.

Some spectators said there appeared to be two explosions.

"It was like the fireworks that had shot off and then they shot across the street and exploded again," said Dave Cleveland, who was across the street from the launch area.

Most of the injuries were described as minor.

The fireworks display was sponsored by the Charles City Jaycees.