A personal injury lawyer walking through a shopping center parking lot to his storefront office was shot in the back of the head Wednesday by an unknown assailant who fled in a minivan, police said.

The shot that killed the lawyer was fired at point-blank range shortly after 9 a.m. Wednesday, Northampton Township Police Chief Barry Pilla said.

The victim worked at Terry D. Goldberg & Associates. Police did not immediately release his name because not all of his family had been notified. He died at St. Mary Medical Center in Langhorne.

No arrests had been made as of early Wednesday evening and no motive was known. Police are seeking the public's help, Pilla said.

"We're specifically interested in anyone that may have been traveling north or south on Buck Road in the vicinity of the scene between 8 o'clock, 7 o'clock in the morning until 9, 9:15," Pilla said.

Police plan to stop motorists in the area Thursday morning in hopes of finding someone with information, Pilla said.

Police stopped someone driving a vehicle similar to the one the gunman fled in and questioned him, but determined later Wednesday that that person was not the gunman.