The incident happened just before 9 a.m. Tuesday on the 3900 block of Ford Road, just hours after the city's blue-collar workers' union, DC 33, went on strike.
According to police, 59-year-old Carnell Wilder approached a PGW worker who was operating a digger loader and asked, "Why aren't you striking?"
He then proceeded to stab the rear left tire of the loader with a knife, causing it to deflate.
Wilder injured his hand while damaging the tire, and was transported to Penn Presbyterian Medical Center to be treated before being transported to the Police Detention Unit.
Police continue to investigate.