Simi Valley fireworks explosion caused by early detonation

Authorities on Friday said they believe at least one pyrotechnic device prematurely detonated in its mortar during a Fourth of July celebration in Simi Valley on Thursday night, causing a chain reaction that tipped over other pyrotechnics and launched them into the crowd of spectators.

The major fireworks malfunction at Rancho Santa Susana Community Park at 9:20 p.m. injured at least 28 people, who suffered minor to severe injuries. An estimated 8,000 to 10,000 people were gathered to watch the professional fireworks display.

Simi Valley police Cmdr. Blair Summey said that after the early detonation, a group of live canisters fell over like “dominoes.” One or more of them fired into the crowd of spectators, the closest of whom were about 800 feet away.

DRAMATIC VIDEOS OF ACCIDENT

“These things were coming through low. They were skipping along the ground,” Summey said. “Some of these projectiles, they were exploding as they were coming out of the canisters.”

The 28 victims ranged in age from 8 to 78 years old. A total of 20 people were taken by ambulance to area hospitals. Four suffered serious, but not life-threatening, injuries. One police officer was also struck in the back by a projectile that cut the leather on his belt, Summey said.

The California Occupational Safety and Health Administration was notified and will also investigate the incident.

The show was sponsored by the Rotary Club, which hired Bay Fireworks, a New York-based company that has produced events for Walt Disney World, NASA and the Republican National convention. Bay Fireworks said it had no immediate comment, but expected to release a statement sometime Friday morning.

Photos: Simi Valley fireworks explosion

Video footage showed fireworks exploding at ground level and into the crowd as people screamed and ran for cover. Police said that after the initial chaos, the crowd left in an orderly manner.

“There was a big boom. Everybody started running down the street. People were screaming,” said Justice Allen, 17, of Simi Valley. “Everybody was just terrified. People hid in bushes.”

Allen said she had just arrived at the park after getting off work when fireworks started flying over the fences and sparks passed by her and her friend.

Another witness, Annisa Wynn, told KTLA-TV Channel 5 that the explosion occurred about two minutes into the show. Fireworks suddenly began shooting sideways along the ground into the crowd instead of up in the air, she said.

“The fireworks were so close, you could see them on the ground,” Wynn said. “It never happens this way. People were screaming.”

Amid the chaos, Ventura County firefighters set up a triage center in the park, where they treated adults and children, many of them hit by flying debris. Some people were taken by ambulance to area hospitals.

Most of the injuries were described as shrapnel-like injuries or burns. No fatalities were reported.

Taken to the hospital were four people with moderate to severe injuries and 16 with minor injuries. The rest were treated and released at the scene.

Simi Valley police Cmdr. John Parks said the Fourth of July event was heavily staffed with police, park rangers and firefighters who were able to treat the injured almost immediately after the explosion.

Parks also said the public cooperated with authorities and quickly evacuated the park after the blast.

Hazciel Vidrio, 26, of Simi Valley, said he and his family have attended the event the last several years, but “this was completely unexpected.”

After four or five rockets went straight up, he said, there was a loud blast and he realized that something was wrong.

“A lot of kids were screaming and crying,” Vidrio said. “People were trying to get away from the fireworks as fast as they could and were running into each other.”

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Twitter: @emfoxhall

emily.foxhall@latimes.com