A small medical transport plane crashed into a residential area in north-east Philadelphia on Friday night, setting homes and vehicles ablaze.
The jet was on a medical transport mission, carrying six people.
Here's what we know.
What happened?
According to the US Federal Aviation Administration, the medical transport jet departed from Northeast Philadelphia Airport at 6:06pm Friday, local time, en route to Springfield-Branson National Airport in Missouri.
The plane quickly disappeared from radar after taking off and climbed to an altitude of 1,600 feet. It was reportedly airborne for only about 30 seconds before it fell from the sky.
It crashed at a busy intersection near Roosevelt Mall, an outdoor shopping centre with dozens of stores and restaurants in the residential neighbourhood of Rhawnhurst.
How many people were on the plane?
There were six people on board the plane.
The medical transport jet was carrying a child patient, her mother and four crew members.
The child had been treated in Philadelphia for a life-threatening condition and was being transported home, according to Jet Rescue spokesperson Shai Gold.
Ms Gold told local broadcaster NBC the child's treatment was sponsored by a third-partner charity.
"She did her course of care. She was going home," she said.
"She fought quite a lot to survive, and unfortunately this tragedy [happened] on the way home."
A spokesperson from Shriners Children's Philadelphia hospital told NBC the girl was one of its patients. The hospital said it was "heartbroken" by the news.
The flight's final destination was to have been Tijuana after a stop in Missouri.
All six people aboard were from Mexico.
The company said no names of the people involved would be released until family members were notified.
"When an incident like this happens, it's shocking and surprising," Gold told The Associated Press.
"All of the aircraft are maintained. Not a penny is spared because we know our mission is so critical."
How many people have died?
All six people onboard the plane died, according to a statement from the office of Philadelphia Mayor Cherelle Parker.
"Many people on the ground — in parking lots, on streets, in cars and homes in the area — were injured, but the number of injured is yet to be released," the statement added.
The statement also confirmed the crew members onboard the plane included a doctor, a paramedic, the pilot and a co-pilot.
What type of plane crashed in Philadelphia?
A Learjet 55 which, according to data from FlightRadar24, had been in service for 43 years and was registered in Mexico.
The plane is owned by Jet Rescue Air Ambulance, which is registered in the US and Mexico.
The company describes itself as "Mexico's leading, largest and most experienced air ambulance service", and reportedly specialises in the transportation of paediatric patients.
Its fleet includes 10 Learjets and one AirBus helicopter.
Who is leading the investigation?
The National Transportation Safety Board (NTSB) will lead the investigation into the incident.
Pennsylvania Governor Josh Shapiro said 45 state troopers were on the ground assisting local law enforcement.
