At times, Jentzen appeared both a bit bashful and overwhelmed by the contingent of family, firefighters, reporter and photographer at the fire station. He only would nod when asked whether he was having fun.
Jentzen posed for photos while standing on the running board of a pumper truck inside the garage, and accepted a red plastic fire hat as a gift.
Engineer Tom Muffler showed Jentzen a shiny metal circular protrusion on the front of a pumper.
"That is where the siren noise comes out," Muffler said, pointing to the speaker.
The child and his mother then climbed into that pumper.
Not done yet, there was even more fun in store.
Jentzen headed to a wooden house cutout with "flames" in the windows and door used in the AFD's annual open house. The little boy expertly "doused" the fires three times with a thin yellow hose spouting water, each bit of flames flopping behind the cutout and disappearing. At one point, he even sprayed Sebold a bit, eliciting laughter from observers.
It then was time for a surprise visit from friendly, furry Sparky the fire dog.
"What are you supposed to do if your clothing is on fire?" Sebold asked Jentzen as he looked at the educational mascot. "You stop, drop and roll."
Sparky then did just that.
Sparky led the boy to the firehouse's dining area, where Jentzen, his grandparents, mother and firefighters enjoyed hot pizzas that Schiber brought to the station. While riding in the firetruck, Jentzen had told Harris that pepperoni was his favorite pizza.
Both fathers, neither Deputy Chief Mark Harris nor Sebold could remember the department having a special event such as Friday's for a seriously ill child in their cumulative 38 years of service.
"This is fantastic," Harris said.
Carol Bolinger said Jentzen is a joy to the family.
"Jentzen is just contagious; you just love everything about him," she said.
Robert Bolinger, pastor at Greater Life Church in Alton, said the outing was good for his grandson.
"I think it lifts him up," he said. "He has points of depression, and the chemo negatively affects him."
Jentzen also is the son of Chuck Felt; he has two sisters, Chesnee, 11, and Ava, 7.