The Learjet 55 went down just after takeoff, creating what witnesses described as a massive fireball, shaking houses and leaving a chaotic street scene.

Jet Rescue Air Ambulance said it was unlikely anyone on board survived the Friday crash. Nineteen people on the ground were injured, Philadelphia Mayor Cherelle Parker said.

It could be days — or more — until authorities are able to confirm the number of dead and injured, said Adam Thiel, the city's managing director. As of Saturday morning, officials confirmed seven dead — six on the jet, one person on the ground — and 19 injured.