Mother and child among seven killed in Philadelphia medical jet crash

Speaking at a news conference on Saturday, Philadelphia city managing director Adam Thiel said it would probably be "days or more" until officials are able to confirm "the number of folks who perished in this tragedy and the outcome of those who were injured".

He added that there is still "a lot of unknowns about who was where" when the crash happened.

The girl being transported to Mexico had just finished medical treatment for a life-threatening illness at Shriners Children's Hospital in Philadelphia.

Earlier on Friday, staff had thrown her a party to celebrate, hospital spokesman Mel Bower said. He added that staff who treated her had been "impacted very deeply" by news of the tragedy.

The flight was bound for Springfield, Missouri for a short stop-over, before continuing onto Tijuana.

The plane left Northeast Philadelphia Airport at about 18:07 local time (23:07 GMT) on Friday, rose to 1,500ft, turned slightly right, then slightly left, then began a steep descent, National Transportation Safety Board (NTSB) officials said.

The crash occurred less than four miles (6.4km) away. Flight logs show the plane was in the air "for only a minute" before it crashed, Mayor Parker said.

No issues were reported from the plane to air traffic control, and controllers who attempted to get a response from the flight crew did not receive one, NTSB chair Jennifer Homendy said.