A man driving down a Pennsylvania highway shot a recent high school graduate in the head, killing her during a road rage incident that authorities described as a high speed "cat-and-mouse game" as the two tried to merge into a single lane.

Bianca Roberson, 18, was shot in West Goshen on Wednesday, the Chester County District Attorney's office said. Her car veered off the road and was later found in a ditch. The shooter fled in a red pickup truck, driving partly along the shoulder of the highway until exiting the road. He is still at large.

Authorities said the driver is a man of medium build, 20 to 40 years old with blond or light brown hair. Police have released a sketch of the man based on an eyewitness account as officials continue their manhunt for the suspect. His truck was described as a red pickup with faded paint.

Roberson had just graduated from Bayard Rustin High School in West Chester. She was headed to Jacksonville University in Florida in the fall.

"Bianca had her whole life ahead of her," said West Chester Area School District Superintendent Jim Scanlon. "What should be a time of great joy and celebration in a young person's life has turned into a horrible tragedy."

"We were all excited for her," her father, Rodney Roberson, told WCAU-TV. "She was excited. We were just happy for her."

District Attorney Thomas Hogan called the road rage shooting a "totally random, senseless act of violence."

"Every cop in three states is looking for this red pickup truck," Hogan said.

Anyone with information is asked to call West Goshen police. There is a $5,000 reward for information leading to the suspect's arrest.

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