If a wing tip was found 12 kms away, imho this very case has some similarities with both Ceiba 738 and GOL 738 (both coliding with exce/biz jets) but however with different outcomes...in GOL case survived the Bizjet, in CEIBA survived the 738.
Could it be the case and being China such a military country they had some midair colision with an UAV, Drone, mil device, etc?