No. The largest number of people who have been killed, the largest number of journalists who have been killed, have been Tamils. But Lasantha Wickramatunga, for instance, and Upali Tennakoon-the two cases I mentioned--are both Sinhalese. The targeting seems to break down not on ethnic lines so much anymore as on political affiliations and whether people are critical or not.
I'd also like to point out that while we have this number of people killed, we also have eight people who feel they have fled their country to save their lives. These are people who were not killed and who, frankly, do not wish to go back any time soon. Their attitudes cover a wide range of responses, and in all honesty, I've been asked not to mention names or certainly make targets or bring publicity to their cases. Many of them want to return to their families, their homeland, their careers, but feel they don't have the protection from the police--even when they ask for it, and it's been withdrawn at times--to feel they can return home safely.
So in addition to that number of journalists who have been killed, also consider these at least eight other people, really. And there's a wide range--they are Sinhalese, they are Muslim, and they are Tamil--who frankly are afraid to go home specifically because they fear being killed. Add those to your mental list of people whose lives are in danger.