In this chapter, Long John Silver and the rest of the mutineers are on the island.

Tom (who is not a mutineer) comes upon Silver unexpectedly and starts talking to him.  Silver won't even let Tom shake hands or come near him -- he jumps back out of the way when Tom tries.  Tom sees the body of Alan, dead. (So that's one person who's killed).

At that point, he walks away from Silver.  Silver throws his crutch like a spear, hitting Tom in the back.  Then he jumps on Tom and stabs him to make sure he's dead.