In the meantime this news was reliable enough for www.phayul.com (a Tibetan online newsmedium) and for www.unpo.org as well (UNPO being the global organization in support of the UNrepresented Nations and Peoples) to publish it too. And Free Tibet asked for the UNHCR to look into the allegations immediately.
It's a rarity that there are foreign (western) eye-witnesses to such shootings and "able" to report. But tragically enough they have not been uncommon on the beautiful pass of Nangpa La, where trekkers too are allowed to walk.

Meanwhile the messages gave Reuters enough reason/confidence apparently as well, to bring below news:

Reuters Alert Net 04 Oct 2006 12:25:28 GMT

Reuters India Wed Oct 4, 2006 6:50 PM IST

So, beware of the neighbours... . . . .