Twenty-eight people have been injured due to malfunctioning fireworks at an annual July 4 show north-west of Los Angeles.
Twenty people were taken to hospitals late on Thursday with minor to moderate injuries after the blast at a Simi Valley park.
A video clip shown on KCAL-TV shows a pair of firework blasts at or near the ground. It was not immediately clear how close people were to the blast's origin.
Simi Valley is about 40 miles north-west of Los Angeles.