Johnson was working as a flagger on a construction project on the freeway -- as a side job. Her main job was helping her mother run the Big Creek General Store.
Friends say Regan was destined for big achievements. And while her life was cut short friends say she certainly had an impact on those around her.
More than 200 people gathered to remember Regan Thursday.
"She was such a good influence, I'm so grateful to have known her in such a formative period in my life. I believe I'm a better person for it," said high school friend Ramneek Batth.
Kingsburg's Memorial Park was filled with candles and broken hearts during the vigil.
"I knew that she was going to really do something in the world. And I guess she has, just all the people talking tonight, shows that her spirit is living in all of us," said Cynthia Bouccola, Regan's high school English teacher.
Regan graduated from Kingsburg High School - and went on to Fresno State where she received a teaching credential.
But her dad says she left her dreams of being a teacher behind. Instead, he says Regan wanted to spend her time helping her mom run the Big Creek General Store.
A store employee says just a few days ago Regan told her mom she eventually wanted to take over the family business. That new dream was never realized.
Regan was struck by a car inside the construction zone on Freeway 99 near the Clinton off-ramp in Fresno.
The CHP says 26-year-old Alyssa Villanueva drove her car into that construction zone and killed Regan. Villanueva was arrested about 10 hours later. The CHP says she fled the scene and tried to hide her car. They also say she was drunk at the time of the accident.
Investigators are charging her with homicide, but ABC30 legal analyst Tony Capozzi says the DUI may be hard to prove.
"You need to have witnesses to say she had been out drinking, how much she drank, how much she would've eaten, all these different factors come into play," Capozzi said.
He says prosecutors could be forced to file vehicular manslaughter or hit-and-run causing death. That processes, however, isn't on the minds of this crowd. For now - they're just trying to come to grips with losing Regan.
Funeral Services for Regan will be held next Wednesday at the Kingsburg Cemetery.
In the meantime, employees at the Big Creek General Store say they're doing their best to keep the store open while Regan's family spends time together.