Passerby News reported on violent fights between Buddhist monks in Cambodia. This pehnomenon, of people who are supposed to be on the same side, but are fighting violently, is not new.
European history is full of blood shed by one religious fraction against members of the same religion. . This existed even in early Christianity. The Albigensian Crusade of 1208 is a first crusade, which was basically aimed at fellow Christians (don't worry, Jews have suffered too, as they always have during crusades).
In world history, Slave trade relied on the fact that some clerics allowed Jihad against Muslims:
[...], some Muslim leaders have justified Jihad (holy war) against Muslims that were perceived as "heathen" (basically, Muslims are not to wage war against another Muslim) and as the norm of the time was, captives were enslaved.
Interestingly, many of the pictures I found online are of Buddhist monks fighting each other, something that might contradict with the Western layman's notion of Buddihists as peace lovers (something that has to do with post-1960s images and ideas than with actual historical facts).
Korea: Fighting at the Chogye Sah Temple, Seoul
(More about temple violence in Korea:
Monks charged over temple violence )