The NTSB has released a photo of a potentially vital piece of evidence that could help answer several questions left unanswered after a devastating crash rocked a Philadelphia neighborhood last week.

Mayor Cherelle Parker said five people are still hospitalized following a fatal medical jet crash in Northeast Philadelphia, three of whom are in critical condition.

Preliminary flightpath analysis indicates the ambulance Learjet 55 which crashed in Philadelphia had climbed to about 1,500ft before steeply descending and striking the ground. Its high-energy impact spread pieces of wreckage over a wide area of a suburb about 2.