Looks like one engine landing on a gas station, which caused even more fire.
Preliminary reports are explosion/catastrophic engine damage/failure. Not ruling terrorist action out, but seem to be leaning away from it. All bags at JFK are x-rayed, both carryon and checked. If I was a gambling woman, I'd put my money on catastrophic equipment failure.
The plane had a basically full pax load, and based on the destination, it's safe to assume a full cargo load as well. The Airbus 300 has two wing mounted engines. The plane was climbing, not cruising,this with the above factors makes control of the equipment with only one engine dubious at best.
Anne