I never heard of one shooting up a school church or whatever.

First off, one must be very careful of generalizing to an entire group from the actions of a small sample [1]. Using the metric of whether there have been trans people who have engaged in mass shootings is quite reductionist, and is a faulty generalization — if I am to interpret what you said to mean that “conservatives” are “against” all trans people because they think that they are all responsible for “shooting up” schools and churches. Second, to address your belief, to my knowledge, there has been at least one instance of a school shooter being trans [2].