Yes and there was a song.
If I remember, protestors were marching on the ROTC which was next to a big commons area in the middle of the campus. Someone or many in the crowd threw things at the soldiers who were attempting to protect the ROTC building. Probably there was contagious fire after one gun was fired. The National Guardsman had rifles. Rifle bullets go a long ways and are deadly.
Most likely no one who threw anything was killed or wounded only the young kids who were doing nothing but there protesting or just walking to class.
Probably more young Americans died that day in Vietnam.
Nixon was blamed, but he had nothing to do with it.