Around 175,000 people turned up for Roar on the Shore to see 110,000 fireworks set off in under 60 seconds from the barge between Bournemouth and Boscombe piers in Dorset last night.
But instead of rockets shooting to the skies, the event was over in about six seconds as the metal barge appeared to explode, with flames spreading across the deck.
Visitors also complained about delays of up to three hours to leave the town as the roads became gridlocked.
Colleen Gallagher, a hypnotherapist from Bournemouth, was watching from the beach at Boscombe pier.
She said: "I felt so sorry for the organisers because it was obvious everything went off in one hit.
"It was a big silvery spray which lit up the beach and then there was just a big cloud of smoke and a few squiggly, short rockets that went up randomly from the fire.
"There had been such a build up, everyone held their breath with anticipation for this roar but then there was nothing.
"Never mind under 60 seconds, more like six seconds.
"It was a bit of a damp squib."
Auditors said last night that a new record had been set and it will now be verified by Guinness World Records.
The current Guinness World Record for the most fireworks set off in record time was set in 2006 with 56,645 fireworks in Plymouth.
Visitors at that event described the sky turning white as the fireworks shot into the air and lit up the night sky.
Artist Sarah Shirtcliffe, from Bournemouth, said: "I don't know what happened. I waited for this spectacular display but it made a boom noise almost like a bomb exploding and then there was nothing.
"The big explosion was very beautiful but we were expecting to see lots of wonderful fireworks in the sky for 60 seconds, one after the other."
A spokeswoman for Bournemouth Tourism said the technical experts at Fantastic Fireworks, which conducted the fireworks display, used a shorter fuse for safety reasons because of the strong winds.
"A huge explosion over a longer period of time could have blown on to shore," she said.
"It went off quicker than they thought it would due to the wind and weather conditions.
"It didn't meet everybody's expectations which is unfortunate but we did break the record which is absolutely fantastic.
"It's not something you can practise, there's an element of surprise involved.
"We have never seen that many people along the whole of the seafront for any event over the last 15 years.
"Maybe that's why we had some disappointed faces. Nobody has ever seen 110,000 fireworks set off in under 60 seconds."
Ruth Downing, 33, from Bournemouth, said: "It looked like the barge just exploded and then caught fire. I think the wind might have caused problems.
"It was very disappointing not so much a roar as a growl.
"We thought it would be rockets exploding in the sky in this amazing fireworks display, but instead if you blinked you would have missed it.
"It was just a big bang, a blinding flash and then flames.
"That was probably the most exciting bit because it looked like the barge was on fire."
A Coastguard spokesman said: "There was a fire on the barge but it was quickly extinguished. No-one was hurt and no help required.
"It was put out with a fire extinguisher. It wasn't a big fire but something caught fire."
Dorset Fire Service said its firefighters did not attend the "small fire" on board the barge.
The record attempt was set up to launch the town's second annual air festival and raise money for Help for Heroes.
Around 750,000 people are expected at the four-day air show to watch displays including the Eurofighter Typhoon, Team Guinot Wingwalkers, The Yakovlevs, The Blades, The Matadors, The Red Arrows and Black Cats Helicopter Display team.
It is the largest event of its kind in the UK, Bournemouth Tourism said.
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