Authorities were trying to figure out what caused fireworks to explode at ground-level injuring 30 on July 4, 2013 in Simi Valley.
Officials with the California Fire Marshals Office were expected to arrive in Simi Valley as early as Monday to investigate the cause of Thursday night's explosion at a Simi Valley fireworks show that injured at least 41 Fourth of July revelers.
As many as 10,000 people were settling into their seats for the Rotary Club of Simi Valley’s 4th of July Firework Show at Rancho Santa Susana Park in Simi Valley when a plume of red and white bursts spread across the ground, police said.
At least 41 people ranging in age from 8 years old to 78 years old suffered injuries, mostly from shrapnel and projectiles, officials said. Four suffered serious, but not life-threatening, injuries.
Authorities initially indicated the cause appeared to be fireworks that detonated prematurely from a a launching station that fell over, knocking over a row of others. But officials were trying to determine why the launching station fell over.
Foul play was not suspected and it appeared to be an accident, officials said.
The fireworks company, Bay Fireworks, said in a statement that it regrets the injuries, and planned 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 July Fourth celebration has been sponsored by the city and the local Rotary Club for the past 43 years.
The company, based in Bethpage, NY, has produced events for NASA, Walt Disney World, Legoland and the Republican National Convention, according to the company's website.
The mishap came a year after a fireworks show in San Diego exploded in about 20 seconds and sent multiple bulb-shaped explosions over the bay.
The show's producer blamed a "technical glitch," saying an error in its computer system caused tens of thousands of fireworks on four barges to go off simultaneously with a single command.
That show was not produced by Bay Fireworks.
Other fireworks mishaps in the U.S. Thursday:
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