A medevac plane has crashed in Philadelphia with a child and five others on board, the air ambulance company that operated it has confirmed.
Jet Rescue Air Ambulance said its aircraft crashed with four crew members, one paediatric medical patient and the patient's escort on board on Friday.
"At this time we cannot confirm any survivors," the company said in a statement.
State and local officials said late on Friday they could not yet confirm how many people may have died on the ground after the plane slammed into a heavily populated portion of the city.
Pennsylvania Governor Josh Shapiro told a news conference at the crash scene that "we know there will be loss in this region."
"We want to offer our thoughts and our serious prayers for those that are grieving at this moment."
The crash follows a collision of an American Airlines jet and a US Army Black Hawk helicopter over Washington DC on Wednesday, which resulted in 67 deaths. It was the deadliest airplane crash in the United States since 2009.
The Federal Aviation Administration said six people were on the Learjet 55 that crashed about 6.30pm on Friday (local time).
Local media reported it was near the Roosevelt Mall in northeast Philadelphia and that there were multiple injuries on the ground.
Video aired on local TV stations showed the plane in a sharp dive before hitting the ground and exploding in a massive fireball.
Philadelphia Mayor Cherelle Parker told a press conference at the scene that several houses and cars had been engulfed in flames. She said the situation is "all hands on deck, that's where we are right now."
Officials said it was not clear what led to the crash. The weather was cold and rainy and with low visibility when the plane went down.
The air ambulance had left Northeast Philadelphia Airport and was headed to Springfield-Branson National Airport in Missouri, about 1800km to the southwest, the FAA said in a statement.
A large fire and several fire trucks were visible at the crash scene in images broadcast by the Philadelphia CBS affiliate. The station said the status of victims was not immediately known.
About two hours after the crash the fires were mostly out, according to TV images.
The Philadelphia Office of Emergency Management said on social media there was a "major incident" in the area of the reported crash but provided no other details.
Neither the Philadelphia police department nor the fire department immediately responded to requests for comment.
