I don’t have much backinfo, but apparently it’s the members the FDN (Família do Norte) Brazilian gang, killing a member of a rival gang (Comando Vermelho – Red Command).
In the video, the killers decapitate the victim inside a water tank. The victim’s mutilated face shows signs of previous torture. After the decapitation, a killer buries the knife in the victims abdomen and cuts open his chest, as if to tear up the heart. The video ends before any disembowelment is shown.
Props to Best Gore member @zebool for the video: