CHESTER COUNTY, Pa. -- A manhunt is on for a suspect who authorities say gunned down a new high school grad, causing her car to veer off the road Wednesday, reports CBS Philly.

Chester County District Attorney Tom Hogan announced Thursday night that 18-year-old Bianca Nikol Roberson was shot in the head by a man driving a pickup truck.

"A red pickup truck merged in at the same time and the man in the pickup truck pulls out a gun and shot her in the head, killing her," said Hogan.

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On Wednesday afternoon, police found Roberson inside her car, which was lying in a ditch.



Investigators say the pickup truck was seen next to Roberson's car before the deadly encounter, then sped off.

"To that person to that man who fired that shot turn yourself in now. Every second you are out there, you are only making this worse for yourself and making this worse for this young lady's family," Hogan said.

It was, he said, a"totally random, senseless act of violence."

Roberson's many friends describe her as loving and full of laughter.

She had just graduated from Bayard Rustin High School in West Chester two weeks ago and planned to attend Jacksonville University in Florida in the fall.

"This is a time of joy and celebration in a young person's life and for her family and it has been replaced by just utter sadness and tragedy," said a school spokesperson.