It happened around 12:45 p.m. at the Lukoil on the corner of Greenwood Avenue and Chambers Street across from Trenton Central High School.
The attendant suffered a wound to the head, which police earlier believed was a gunshot wound. On Tuesday, police said the wound was actually from the victim being beaten with the handle of a gun. That victim could be seen talking with EMTs after the incident.
He was taken to the hospital in an unspecified condition.
The suspect fled on foot.