Investigators say the man searched for his victims at Morris Market on the corner of 15th and Morris streets around 8:30 p.m. on Monday, Nov. 7.
Surveillance video released by police Wednesday shows the victims walk out of the store and the attacker puts on a mask then follows them.
He repeatedly punches one victim and knocks the second unconscious.
Police say he stole valuables from both victims and took off.
The suspect was wearing an Amiri shirt with a skeleton and roses on it.
Anyone with information is asked to call police at 215-686-3013/3014.