KNOXVILLE, Tenn. (WVLT) -- Four-hundred thousand people were rubbing shoulders in Downtown Knoxville for Boomsday, so that means there was plenty of planning.

Volunteer TV spent Sunday morning near the Henley Street Bridge, as crews put the finishing touches on the festival set up.

"There's probably four or five miles, or maybe more than that, of wire," Dean Brannam a Pyro Technician said. "There's mines. There's shells. There's cakes."

The guys from Pyro Shows worked almost around the clock for four days. And their efforts were gone in a flash.

"It all goes up in about 20 minutes," Brannam continued.

It's all worth it, though, for the Campbell County-based company.

"It's really a thrill for us to be able to actually work this close to home and sort of entertain our family and friends with a show, also," Brannam told WVLT.

The big show may end up top, but things started sizzling under the bridge early in the morning.

"Started [Saturday] night to do the initial setup until about seven o'clock [Sunday] morning, and we are now preparing the food," Margaret Stone with the Greek Corner said.

Vendors from the Greek Corner have been a staple at Boomsday since the festival started.

"Compared to the very first Boomsday, it's really grown. It's become a huge festival and one of our favorites to work," Stone added.

They keep coming back, just like neighboring vendor, Bill Davenport.

"The atmosphere that happens around here, and it is one of the largest fireworks displays that's around," Davenport said explaining why he enjoys Boomsday so much.

Davenport says while Boomsday keeps growing, it still has a hometown feel.

"The fireworks are locally around here, and it's a local home show for us."

And vendors say that's what makes Boomsday so special.