The fireworks accident in Simi Valley on Thursday night was captured in numerous cellphone videos.
The videos offer various angles of the accident, which left at least 28 people hurt.
This one was taken close to where the fireworks exploded into spectators:
This is another view from the event:
This video was taken some distance away and offers an overview of what happened:
The extent of the injuries was not fully clear, but officials said they ranged from minor to severe.
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.
"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.
Jai Kohli, 30, of Pasadena, said there were about 10,000 people at the show and there was a lot of confusion after the explosion occurred.
He recalled that one of the fireworks exploded low to the ground with a lot of force. "People around me instinctively ducked," he said.
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."