Her husband, Jason, had been working as a firefighter in Montgomery County and was dispatched to the scene for emergency rescue.
What started out as a seemingly routine call would change his life forever.
"I did respond and arrive on location to see our vehicle and to realize that it was my wife and unborn daughter," he recalled. "The hardest part was going home and telling our two boys that their mom and sister weren't coming home."
In the aftermath of the tragic accident, Jason said he got immediate financial support from the nonprofit, Montgomery County Hero Fund through capital provided by Families Behind the Badge Children's Foundation.
It's a nonprofit that provides support to families of fallen or critically injured first responders.
He said that support helped him and his family get through an incredibly difficult time. So, when the opportunity to give back fell in his lap a year later, he jumped at it without hesitation.
"That really motivated us to want to give back, to pay it forward, to become a part of something bigger than ourselves," Jason said.
So he and Kellie's sister, Stephanie Miller, decided to help families who may find themselves in a predicament like theirs.
The two joined the Montgomery County District Attorney's "Wheels of Justice" bike team and began training and raising money for "Ben to the Shore Bike Tour," the 65-mile bike charity event from Philadelphia to Atlantic City organized by Families Behind the Badge Children's Foundation.
What started as a mission to help evolved into an opportunity for both Jason and Stephanie to heal as they made connections with people and families who could understand their anguish.
"So much of that was intertwined with our grief process and just getting through the hardest days of our life," Stephanie said.
The two, unsure of what they had gotten into, took the long bike ride for the 2023 Ben to the Shore Bike Tour. It was challenging, but with support from family and friends both Jason and Stephanie completed the ride.
That motivated Kellie's other sister, Jaclyn Miller, and their mother Cindy Miller to take the ride this year.
"I really felt the community that surrounded them," Cindy told Action News.
All four have spent months training every week for the big ride on July 21, and they've raised thousands of dollars along the way to support the families of first responders as some of the top fundraisers for this year's event.
Jack Costello, the associate director of the Families Behind the Badge Children's Foundation, said raising money for their cause is excellent, but nothing beats the power of helping grieving families cope with a tragic loss.
He said that's what the Ben to the Shore Bike Tour has been doing for years.
"They're able to hop on a bike and move forward literally and figuratively," Costello said.
As Jason moves forward with his life, he said the legacies of both Kellie and their unborn child would live on through the family's efforts to pay it forward.
"We're a family of service," he said. "That's what we do. That's who we are."
Families Behind the Badge Children's Foundation said it's already raised $1 million through the more than 2,000 riders who will take the ride to the shore this year.
It's hoping to raise an additional $500,000 before the ride kicks off on July 21. For more information on how you could help head over to ben2shore.org.