Investigators say it all started at about 3:30 a.m., while the off-duty officer was in his black Nissan SUV near Seventh and Willow streets.
It is a section of the city where there is as string of old warehouses that have been converted into offices and restaurants.
Police say the 23-year-old suspect, identified as Al-Tariq Hutchinson of Edgewater, N.J., jumped into the officer's vehicle, demanded money and pistol whipped him across the face.
The officer pulled his gun and fired eight times, investigators said.
Hutchinson was taken to Hahnemann Hospital where he was pronounced dead. Police say he had several prior arrests in New Jersey.
The officer remained on the scene for some time in the back of a police cruiser with towels to his bleeding face. He was then taken to Jefferson University Hospital to be treated for his injuries.
Police say a 22-year-old man was in a car with Hutchinson before the shooting, but that man may not face any charges. Police say he was in the car when Hutchinson got out and told him to keep the car running. Police tell Action News he will not be facing any charges in the case.
Moments later, he told police he heard gunshots. Seeing Hutchinson on the ground, he flagged down police.
That man was being questioned by police.
Investigators found a gun and a pile of money on the street.
Investigators say the off-duty officer -- a 55-year-old veteran of the police department's traffic unit -- told them he was just driving through the area when he was ambushed.
It is unclear why he was there. There are plenty of surveillance cameras in the area, and investigators are hoping they will be helpful in solving this crime.
Off-duty officer robbed just last week
Another off-duty police officer was robbed just one week ago.
Philadelphia police officer Martin Campbell was robbed and shot in the leg while off-duty.
Campbell's friend, Rasheen Allen, was shot and killed during the holdup in Hunting Park.
Officer Campbell survived.
There is a $15,000 dollar reward to help track down the two men who attacked them.
