There was apparently, possibly an engine explosion. But nobody really knows what happened.
Air travel in the Congo is a mess. There are no radar systems, security is spotty-to-nonexistent, and, as this expert puts it, "Congo is just a graveyard for airplanes." You don't want to know some of the things I've seen and experienced, or the near-misses with death my friends have had.
I'm willing to bet the pilots were either Congolese, Senaglese, French, or South African. Those pilots tend to be hugely resourceful, and, more importantly, they know how to crash in such a way that people survive. People don't survive crashes that happen with the eastern European and Russian pilots, who are usually seriously hung over or drunk when they fly. I'm dead serious about this. I won't board their flights.