(CNN) When most of the country was going ooh and aah over Fourth of July fireworks displays, San Diego spectators were treated to a spectacle that lit up the night sky -- for all of 15 seconds.
Thousands had gathered at beaches and parks to catch a glimpse of the annual "Big Bay Boom" show on Wednesday night. Some camped out for hours to see the fireworks that ignite around the San Diego Bay on Independence Day.
An unknown glitch caused the fireworks to explode all at once, botching the show and bewildering spectators.
Others fled into the night as four big balls lit up before their scheduled time, adding to the confusion.
The Big Bay Boom was a Big Bay bust.
"It shook the whole building. I thought it was a bomb or someone was shooting everybody," said Teagan Hamblin, a Kansas resident who was visiting San Diego. "Car alarms, every kind of noise came on. It was really unexpected."
After the explosion, the crowd went quiet as everything went dark, spectators said.
However, the music synchronized to go with the fireworks played on, according to Hamblin.
"There was "Proud to be an American," "Born in the USA," some Taylor Swift songs and lots of music with "America" in them," she said.
San Diego resident Jennifer Boyd said the incident caught her offguard.
"I was waiting around wondering what happened, wondering whether there was going to be a do-over," she said.
There was no do-over.
Organizers, who had promised a 20-minute show that included fireworks from four barges, canceled the show.
"I don't think anyone is mad about it," Hamblin said. "It's not what we expected, but it's kinda like a big joke now."
The company behind the display said it is working to determine what caused the entire show to be launched in seconds.
The show was all choreographed, but the explosion happened at once, according to August Santore of Garden State Fireworks.
"This is very uncommon .... there was nothing in the pyrotechnics that went wrong," Santore said. " It was the electronics."
There were no casualties or arrests reported, police said.