At least seven people died when a medevac plane crashed in Philadelphia, including six Mexicans aboard the plane and one person who was on the ground, Mexico's president and Philadelphia's mayor said.

Philadelphia Mayor Cherelle Parker told a press conference that the person who died on the ground on Friday had been in a car at the site of the crash.

"Thus far, our count is that there are 19 injured victims," Parker said.

Separately, Mexican President Claudia Sheinbaum said in a post on X that she had asked consular officials to support the families of the six Mexican citizens who were on the plane and died when it crashed.

Authorities sifted through burned cars and charred debris on Saturday to gather clues that might explain why the plane exploded into a fiery ball as it crashed to the ground.

Philadelphia City's managing director, Adam Thiel, said it could be days until authorities are able to confirm the number of dead and injured.

Jet Rescue Air Ambulance, based in Mexico and licensed to operate in the United States, on Friday said its aircraft crashed with four crew members, one pediatric medical patient and the patient's mother on board.

The child was a girl on her way home with a final destination of Tijuana, Shai Gold, who works on corporate strategy with Jet Rescue Air Ambulance, told CNN on Friday.

Her mother was also aboard, he said.

With AAP.