A small medical jet carrying a child patient crashed in Philadelphia, sparking a massive explosion and a flurry of questions.

All six people aboard the plane − a pilot and copilot, two medical personnel, a patient and her mother − died in the crash ...

According to the online flight-tracking service Flight Aware, the red and white plane is a 43-year-old Learjet 55 registered to Jet Rescue Air Ambulance, which has operations in Miami and Mexico.