Near the end of The Raid (2011), the lieutenant Wahyu and Dagu reach the boss, then Wahyu kills Dagu. But he is not on the boss' side (and later kills the boss anyway) so why kill his comrade?
Because Wahyu was corrupt and Dagu and Rama figured it out during the raid (the guy in the apartment complex told Rama that Wahyu had been in the building many times before which he would only have known if he was in league with the criminals and Wahyu knew where Tama's office was). Jaka even told him he would go to jail as he had led an unsanctioned and highly dangerous mission and no one else knew about it. They were originally working together as that was the only way they could escape alive (by seizing Tama and using him as a hostage) once Wahyu had Tama as a bargaining chip he realised that he didn't need Dagu and Rama anymore and their knowledge of his corrupt actions would lead to him being incarcarated.
A bit late but I assume it was to ensure for his own survival by taking Tama Hostage for himself. I'm not sure though.