Dude i think you have bad informations.
1. At first give me the sourve of 90% of mass shootings were caucasions or white, i think it means a white race.
2. There were 4 people included. One guy didnt kill all 49 people and injure 20 more.
3. You are white, but you are still racist. And if you are not, then stupid, because there are plenty of mass shooting where a lot of people have died by one man who wasnt white.
4. It is IT, because even though a lot of mass shootings are caused by white people, there are only few against muslim community if any at all. Thats why it is different.