The US Federal Aviation Administration says a small plane crashed in Philadelphia, in the eastern US state of Pennsylvania, at around 6:30 p.m. on Friday.

The FAA says the Learjet 55 plane went down after leaving an airport in Philadelphia.

It originally said two people were on board, but later corrected the figure to six.

The aircraft is reportedly a medical transport plane. Its operator said four crew members, as well as a child patient and an escort were on board, but no survivors have been confirmed.

Video clips from the crash site show multiple buildings on fire and nearby roads strewn with debris.

Citing local police, CBS News said several casualties have been reported on the ground, and that multiple houses and vehicles sustained damage.

ABC News reported an eyewitness as saying: "It was just horrific. I was just driving down the street ... and I just saw a plane basically hit the building and it exploded. The sky lit up."

Emergency crews are responding to the incident by blocking the roads. They are calling on residents to stay away from the area.