They were peaceful until Tibetans were assaulted by Chinese Police/thugs. Then the long-term resentment towards outsiders boiled over and things turned nasty.
To be fair, from the clips I've watched and media reports that I've read -- BBC, CNN, and various newspapers based in the States -- my gut feeling is that both sides need to share the blame, although I still need more FACTS to form a final opinion.
Everybody can agree on the fact that the protests have been going on since March 10, in various Tibetan towns in China and also in other countries like India, Nepal, Australia, Belgium, Canada, the U.S. etc. While a lot of media described these protests as "peaceful," arrests were made in almost all of these cases.
A good friend of mine took part in the anti-NMD protests at the Democratic National Convention. I gave her a ride there and watched the whole thing, so I know what a peaceful protest looks like. Just from the media clips, the protests in India, Nepal and Belgium where the protesters were rushing into police officers with sticks and poles can hardly be called "peaceful."
Was the violence on Mar. 14 triggered by police brutality? It's possible, but without independent verification, I'd be a little skeptical, seeing how people rushing in and tackling and throwing punches at police officers is considered "peaceful" by Richard Gere and the Dalai Lama. Go to BBC.com, search for keywords "tibetan" and "india" and you'll see what I'm talking about.
Besides, police brutality should not be an excuse to start a riot. Hundreds were arrested at the Democratic National Convention, people got pepper sprayed and thrown to the ground and handcuffed, but did they go around setting fire to buildings? -- NO!
With that said, I think it's ridiculous for the Chinese government to say that shots weren't fired or to categorically deny deaths from police gunfire before an investigation has taken place.
I'm sure that most of the people here don't want to see a war between China and the United States due to mis-calculation or mis-understanding -- at least, that's part of the reason why I'm here. On the same token, I'm sure most of you guys don't wanna see any innocent people killed, whether they're Tibetan or Muslim or Han Chinese. So let's just get the FACTS first, shall we?