It appears to be a dual engine failure.
They’re quite unlikely, but with fuel on board, they generally fall into two categories - crew error and fuel contamination.
I doubt it “gelled up”, this jet doesn’t fly high enough, and it was not far enough North.
Now, contaminated fuel remains a possibility. Because of the post crash fire, I would not suspect that they ran out of fuel, but it still is possible that the crew made an error that starved the engines of fuel.