The inmates, who were serving sentences for crimes including murder and robbery, overpowered a jail guard in the southern, coastal town of Siocon late Friday, killing him and seizing his shotgun and pistol, said Inspector Dahlan Samuddin, the area's police spokesman.
Guards and police from the nearby station rushed to the scene, sparking a gun battle that left two detainees dead, he added.
Four inmates as well as two guards and two policemen were also wounded in the shooting, Samuddin said.