The Chester County District Attorney says Bianca Nikol Roberson and a man driving a red pickup truck were trying to merge in the same lane before the case of road rage turned deadly Wednesday afternoon.
"And a man in the red pickup truck pulled out a gun and shot her in the head, killing her," said D.A. Tom Hogan.
Her car veered off the southbound lanes of Route 100 in West Goshen Township and crashed.
Traffic cameras captured images of Roberson's green car and the red pickup.
The driver is described as man between 30 and 40 years of age with a medium build and blonde hair. He's considered armed and extremely dangerous.
Anyone who witnessed the incident is urged to contact the West Goshen Police Department Traffic Safety Division at 610-696-7400.
Highway cameras reveal Roberson and the driver of that red pickup truck, possibly a Chevrolet, had some sort of altercation minutes before spinning out of control.
West Goshen Police Chief Joe Gleason said, "They were jostling for a position or whatever. And unfortunately this gentleman took it to a degree that was just unconscionable."
A second photo shows the red pickup, moments after the crash, fleeing the scene on Route 202 before exiting onto Paoli Pike.
Roberson was a recent graduate of Bayard Rustin High School in West Chester.
Her brother told Action News she was "headed for greatness."
"She was a good girl, honor roll student, looking forward to going to college," said her father, Rodney Roberson.
Choking back tears, Roberson said Thursday that his 18-year-old daughter's death still hasn't sunk in.
Grief counselors will be back at Rustin High School on Friday from 9 a.m. to 11 a.m.
On Thursday Action News learned this is just the latest tragedy for Roberson's family. Four years ago, they lost Bianca's older brother.
Family members say when Wednesday's crash happened, Roberson had just left an area mall. She was shopping for college clothes with her mother and grandmother.
"I hope it's not Bianca." That's what the teen's grandmother said to herself as she passed the crash site Wednesday, intending to meet up with her granddaughter at home.
She had no idea the traffic backup she was sitting in was caused by the crash involving her granddaughter.
"Not one bit," added Aunt Mari Hatton-Hayes. "And then when she saw the police she said she had this crazy feeling."
Police were already at the house to notify Roberson's family that she had died at the scene.
"She's so young. And to go through something like that by herself.... She had to have been pretty scared," said Dontae Alburg, Bianca's brother.
The teen was heading to Jacksonville University in Florida in two weeks for orientation. Her goal was to someday solve cases for the FBI.
Her family is hoping someone, particularly the driver, will help close her case.
"If you don't even think it was your fault, and have a conscience, come forward and give us some closure and explain in your own words what happened," Roberson's father said.