Early Tuesday morning, the vandals got past the barbed wire fence at the Hunting Park facility on the 1900 block of Ruffner Street.
They then used one of PennDOT's own trucks as a weapon.
The vandals rammed the truck into other vehicles, then hit building wall, cracking it, before slamming the truck into the facility's large garage doors.
There were no injuries, but investigators say the suspects caused thousands of dollars in damage. Police believe the entire incident only lasted a few minutes.
The vandals even ripped out the radio of the truck before fleeing.
PennDOT says the building will be able to be repaired, despite the structural damage. However, until repairs are made, the damaged building has been deemed unsafe.
"We're able to salvage the building as a whole. So what we're going to have to do is resupport, rebuild the side wall that enters into the garage area," said Nick Martino of PennDOT.
State police have been out at the facility looking for fingerprints on the vehicle involved.
Initially police said the keys were left inside the vehicle, but now investigators say there is a chance this was an inside job. Normally the keys are removed by the last crew in, and someone is tasked to walk through the entire yard, making sure the keys are out of all of the vehicles.
The keys used normally have fobs on them, but the key inside the vehicle involved did not.
If you have information that might help in the investigation, state police ask that you call them at 215-560-6200.