SIMI VALLEY, Calif. — As many as 10,000 Fourth of July revelers were just settling into their seats for the fireworks show at a Simi Valley park when a bright plume of red and white bursts spread across the ground, injuring 39 people and sending others fleeing for safety.
Police in the city northwest of Los Angeles were still investigating what triggered Thursday night’s explosion. They said the cause was still unknown, although they had earlier indicated that it appeared a firework detonated prematurely in its mortar, knocking over a row of others.
A view of the scene from a distance Friday morning showed groups of mortars held vertically in box-like wooden structures sitting on the ground. In front of them, a number of mortar tubes lay horizontally scattered. Cellphone videos captured fireworks exploding in spheres of sparks close to the ground, with smoke and people screaming.
The victims ranged in age from 8 to 78, Simi Valley police Sgt. Tom Meyer said. A total of 20 people were taken by ambulance to area hospitals. Four suffered serious, but not life-threatening, injuries. Three of the victims remained hospitalized Friday night.
One police officer who ran into the crowd when the blasts occurred had shrapnel tear through his leather belt and clothing, police Cmdr. Stephanie Shannon said. He suffered minor injuries to his back.
On Friday morning, blackened debris from the explosion littered the ground. Huge chunks of shrapnel were still scattered across the park, and the stand the fireworks had been on was sitting, charred, in the middle of a green lawn. Investigators plan to fly over the scene to photograph it and examine the debris, Meyer said.
The fireworks company, Bay Fireworks, said in a statement that it regrets the injuries and is planning a thorough investigation, with results to be made public.
The company also said that injured spectators should contact the Simi Valley Rotary Club to reach the company’s insurer. The annual Independence Day celebration has been sponsored by the city and the local Rotary Club for the past 43 years.
The company, based in Bethpage, N.Y., has produced events for NASA, Walt Disney World, Legoland and the Republican National Convention, the company’s Web site said.