Fourth of July accident caused by 'premature detonation' [UPDATE]

Update, 2:00 p.m.

Officials said at least 34 people were injured when a fireworks platform collapsed during a Fourth of July show Thursday night, a number that rose overnight from 28.

Police said the initial investigation indicated at least one of the fireworks went off early, caused a chain reaction in the pyrotechnics that sent them off towards the crowd.

Simi Valley police Cmdr. Blair Summmey said the live canisters fell "like dominoes."

"These things were coming through low," Summey said. "Some of these projectiles, they were exploding as they were coming out of the canisters."

Police said at least one of the launching stations fell over after the reaction began.

Original story follows

A wooden platform holding the fireworks for a Fourth of July display in Southern California tipped over mid-show, injuring more than two dozen people and sending a crowd into a panic.

Officials said 28 spectators were treated for shrapnel-like wounds and burns after the mishap at Rancho Santa Susanna Community Park in Simi Valley Thursday night. Twenty were transported to area hospitals.

Witnesses said the accident happened about two minutes into the show, when suddenly rockets began shooting sideways at the crowd.

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

"There was a big boom. Everybody started running down the street. People were screaming,” said Justice Allen, another witness. "Everybody was just terrified. People hid in bushes."

Ventura County firefighters, who were already on the scene, set up a triage center to treat the injured. Simi Valley Police Cmdr. John Parks said the event had been heavily staffed with police, park rangers and firefighters who were able to react immediately after the explosion.

Authorities estimated the crowd was between 8,000 and 10,000 people. The crowd was kept at least 350 feet from the launch platform, as required by the fire code, a distance which presumably kept the number of injured down.

Police Cmdr. Stephanie Shannon said there was no indication the accident was anything but.

"Although it is still unknown why the launching station fell over, there are no indications of foul play and it appears that this is an industrial-type accident,” Shannon said. "At this point there are absolutely no indications of foul play. We will try to determine to the best of our ability exactly what happened."