LE calls it a fatal accident when a drunk driver hits someone and kills them. They didn't intend to kill anybody, but it happened, and they still have to take the blame. So, let's say something happened to Dylan but he didn't intend to kill him, it would still be an accident in the eyes of the law.
For example, Dylan smarted off at him, they got into an argument and Dylan started hitting at him and he shoved him away. Dylan lost his balance and fell against something and hit his head and died. That's an accidental death.
All that means is that he indirectly caused his death, but it was not intentional, as in premeditated.
Accidents can range from very minor to fatal, but they are still called accidents.