MADISON, Wis. -- Madison's official Fourth of July celebration got underway on Friday.

Thousands are expected Friday night at Elver Park for the festivities and fireworks.

Those who were working behind the scenes Friday to set up the fireworks show said it takes a lot of work to pull off.

"Everybody thinks you just go and do it in five minutes," said Andy Jaeckel, of Bartolotta Fireworks. "They don't realize the time involved."

Jaeckel does more than 30 fireworks shows a year, and he said Elver is his biggest.

At Friday's show, Jaeckel's crew will use shells ranging from 3 inches to 6 inches -- the bigger the shell, the bigger the blast. The fuses for each shell are about 30 inches long and they light in an instant.

Wooden racks hold the guns that will fire the shells into the air. Spectators will see more than 400 shells in Friday's finale alone. It happens within just 30 seconds.

"We start with a single row," Jaeckel said. "And then we go to a double, triple and just spread them out. There are special display shells that maybe put up a heart or a star or something like that -- special effects."

Organizers moved this year's celebration to July 3 to save costs. Having the celebration on a non-holiday saved the group more than $50,000 in police and security costs.

The fireworks start at dusk Friday, and the festivities are completely free.