The brazen attack happened around 4 p.m. last Friday on the 4500 block of Frankford Avenue.
The video shows the suspect walking up to the 37-year-old male PPA officer from behind and shooting him in the ear and shoulder.
SEE ALSO: Philadelphia Parking Authority officer shot while on duty
Philadelphia Parking Authority officer shot while on duty
The officer, who has been identified by his employer as Timothy McKenzie, collapsed onto the sidewalk before help arrived.
"It's bold. It's brazen and something we're definitely going to do everything we can to solve immediately," said Philadelphia Police Deputy Commissioner Frank Vanore last week.
McKenzie is in stable condition and the PPA and others are praying he makes a full recovery.
It's still unclear what sparked the shooting.
McKenzie is assigned to the Frankford neighborhood and is well-known in the community.
"I speak to him every day. He's a good guy, really nice guy," said Bamba Sisoko of Frankford.
"While Tim continues to improve as each day passes, we must do our part to assist law enforcement in apprehending the criminal who was intent on killing one of our enforcement officers. We hope this $20,000 reward assists our police in capturing this criminal assailant," said PPA Board Chair Beth Grossman.
The suspect is described as a man who is about 5 feet 9 inches to 6 feet tall, with a thin build. He was seen wearing a navy blue hooded sweatshirt, green cargo pants, black mask, gloves and black boots.
The suspect should be considered armed and dangerous.
The City of Philadelphia and The Philadelphia Parking Authority each have offered $10,000 for a total of $20,000 for information that leads to an arrest and conviction of the man in the photos.
Anyone with information on the suspect is asked to call police at 215-686-TIPS.