Sixteen people died and 13 others were hurt.
Muench, wearing a Broncos jersey, told the service that an outpouring of support from across the country has helped those who are still suffering from the tragedy.
"These kind gestures have helped us all along the three-year journey to today. I would like to thank the parents, family members and surviving players that have meant positive changes that are happening in our country because of this tragedy," said Muench, who is now the city's deputy mayor.
"You are certainly making our world a better place."
The church bell rang at 4:50 p.m. — the estimated time of the crash. It was followed by a moment of silence.