Police were investigating what caused fireworks to shoot into a crowd of revelers and injure 28 people on Independence Day in Simi Valley, California, authorities said on Friday.
Shortly after the start late Thursday of a Simi Valley Rotary Club fireworks show about 30 miles west of Los Angeles, fireworks landed in a crowd of 8,000 to 10,000 onlookers gathered in a park, police said.
Officers in a helicopter took aerial photos of the scene of the mishap on Friday to get a better sense of what went wrong, said Simi Valley police spokesman Sergeant Tom Meyer.
"What we understand is potentially one of the launching stations fell over, resulting in ignited fireworks going into the crowd," Meyer said.
It was not immediately clear what caused the launching station to fall over.
The California Occupational Safety and Health Administration will be involved in the investigation, and Bay Fireworks of Bethpage, N.Y., which mounted the fireworks show, is cooperating with the probe, police said.
Twenty-eight people suffered shrapnel wounds and other types of injuries in the resulting chaos, and four individuals had serious injuries, police said.
Most of the injured were taken to Simi Valley Hospital. Those victims ranged in age from 17 months to 71 years old, with a dozen children among the injured, said hospital spokeswoman Alicia Gonzalez.
Injuries ranged from burns and shrapnel wounds to chest pains to trauma resulting from being trampled by the crowd, Gonzalez said. Two people remained at Simi Valley Hospital in fair condition on Friday, one person was transferred to an area hospital specializing in burns and the rest were released, she said.
There was no sign of foul play and the incident appeared to be an accident, police said in a statement. Unexploded fireworks at the scene were disarmed by the Ventura County Sheriff's Department bomb squad.
Los Angeles station KABC-TV showed images of black fireworks debris spread all across the Simi Valley soccer field where the display was staged.
Fireworks spectator Gregory Perkins told the station he was in the front row at the event when "everything went off" in a mass explosion and a cylinder block hit the person sitting next to him.
This was the second year the local Rotary Club used Bay Fireworks for the fireworks show, police said.
Bay Fireworks said in a statement it "will conduct a thorough and complete investigation of this incident and make our findings available to the public."
Simi Valley is home to the Ronald Reagan Presidential Library.
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