Why was Juliano Mer Khamis killed, and who killed him?

Isn't that such a coward terrorist act? What amazed me was the huge number of Palestinian mourners of an Israeli, who served in the Israeli army. It's a shame that peace loving Israelis get killed with cold blood, and it's a shame that not even one Israeli official had anything to say about an ugly murder of such a good peace-loving person. Isn't there any one peace-loving official in Israel?