It happened on the 100 block of South 9th Street, investigators said. A male suspect swiped the backpack from the victim's car while he was fixing a flat tire, police wrote in a release.
A second man "pressed a hard object in (the victim's) side, preventing him from chasing the suspect," authorities said.
Two women were also seen traveling with one of the male suspects, police added.
The suspects fled in a light-colored Honda Odyssey with Pennsylvania tag number LNV-1183, which does not belong to the vehicle.
Anyone with information is asked to call 215-686-8477 or submit a tip on the PPD website.
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