I don't really care if the security guard was an ignorant anti-Semite or that the leaders of this particular Mosque have a history of embracing extremism. There were kids inside, so I am thankful he acted to stop the shooters.
This targeted attack was an act of terrorism. Something we can't accept in America.
It was wrong when an Islamist extremist targeted a synagogue/school in Michigan a few months ago, and just as wrong today when these two lunatics targeted a Mosque/school.
Parents shouldn't fear that kids going to school or families going to worship might not come home. Such places shouldn't need constant security. The normalization of such evil and hate only ensures further violence.
Everything else is a different discussion.
From the Facebook page of Amin Abdullah, the security guard killed in the mosque shooting today