Sampling Technique?

I am writing a report in which I have taken the incidents of bomb-blasts as the population and as the sample, I have taken the incidents in which there were some fatalities. kindly tell me which type of non-probability sampling is this?
Is it Judgmental sampling or Purposive sampling in which the researcher chooses the sample based on who they think would be appropriate for the study as this is used primarily when there is a limited number of people that have expertise in the area being researched.
Also, Kindly tell me what would be my defense if I am asked to justify my sample size? The ume-sakran's table is of no use here.
Kindly reply asap.
Thank You.