I appears to be a Lear 55, that was taking off out of the north Philly airport. That would explain the speed, as they were within a short distance of the runway.
The thing looks like a missile hit.
Nick Sortor
@nicksortor
🚨 #BREAKING UPDATE: The plane which crashed in Philadelphia appears to be a Learjet 55 Air Ambulance from Mexico
It seems to have crashed shortly after take off from Philly’s Executive Airport (PNE)
Fully fueled....