SIMI VALLEY, Calif. (AP) - When a July Fourth fireworks display exploded and sent red and white bursts into spectators at a Southern California park, Paulina Mulkern saw shrapnel heading straight for her 4-year-old cousin.
Mulkern threw the child under a lawn chair, and then shielded her 7-year-old cousin with her body as scorching debris flew overhead.
"You feel the big old heat come right over your back," she said Friday, still shaking as she recounted the explosion the night before that left her with bruises and red marks on her back.
Dozens of people were injured, as many in the crowd of thousands fled for safety. The victims, from 17 months to 78 years old, had burns and shrapnel wounds, and some were trampled, authorities and hospital officials said.
Mulkern said she went into shock after the near-hit, trembling so badly she had to be carried to a road where rescuers stripped off most of her clothes and wrapped her in a blanket.
Police in Simi Valley, northwest of Los Angeles, had earlier said it appeared a firework exploded prematurely in its mortar, knocking over others and aiming them across the field. Fire investigators, however, said later they had not yet determined a cause.
Among the questions investigators were trying to answer was whether the pyrotechnics display was set far enough away from spectators, and even if all the rules were followed, whether those guidelines needed to be revised so that the public is kept farther back from launch sites.
Authorities said regulations require the crowd be kept 70 feet away for every inch diameter of the largest shell used.
The largest shell at the display was likely five inches in diameter, meaning the spectators should have been at least 350 feet away from the launch site at the show put on by Bethpage, N.Y.-based Bay Pyrotechnics, said Ventura County Fire Department Deputy Chief Mike LaPlant.
Police said the fireworks rained down on a crowd that was at least 800 feet away. The distance of spectators from the show will be one of many factors considered by investigators, he said.
"We're just confirming what we feel to be true, which is that the distances were either at or beyond the normal distances, the prescribed distances, for that sized shell," he said.
The company said it regretted that spectators were injured and that it planned to publicly release the results of a thorough investigation.
The blast was among several fireworks mishaps on Thursday, including errant explosions injuring workers at shows in Ojai, Calif., and North Myrtle Beach, S.C., and a fireworks barge that caught fire in Montana at the start of the grand finale.
In the Simi Valley explosion, cellphone videos captured a frantic scene in which fireworks were exploding in spheres of sparks close to the ground, and smoke enveloped the park grounds. People were heard screaming.
Colette Schmidt, who lives across the street from the park and had about 150 guests over to watch the fireworks from her front lawn, said they could tell almost immediately that something went wrong. Two regular fireworks went off, she said, and then others started exploding at ground level.
One hit across from their home, leaving a crater, and bounced twice before shooting up over nearby trees and exploding in a puff of reddish-purple smoke, said Schmidt's daughter, Alessi Smith.
The family herded their guests inside and drew the blinds as sparks and embers rained down. "It was terrible but we were so blessed because we had 150 people here and not one single spark hit our house," she said.
A bomb squad was sent to the park to deactivate the remainder of the fireworks.
On Friday morning, blackened debris from the explosion littered the ground. Huge chunks of black 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.
Authorities said investigators planned to examine the debris and fly over the scene to photograph it.
The annual July Fourth celebration has been sponsored by the city and the local Rotary Club for the past 43 years.
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 because of an error in the computer system that sets off the pyrotechnics. No one was injured. That show was not produced by Bay Fireworks.
Julie L. Heckman, executive director of the American Pyrotechnics Association, a fireworks trade group, said that while the investigation has not yet revealed the cause of the Simi Valley blast, she believes it was probably a product malfunction.
Heckman said the industry takes such incidents seriously, especially when they involve spectators. She also noted that Bay Fireworks has been in business for a long time and has done significant productions.
The company website says it has produced events for NASA, Walt Disney World and Legoland.
"This incident is a dark cloud over the entire industry," she said. "We don't take it lightly."