NPR has a picture of the NG advancing on the students. They are NOT firing; their weapons are a port arms. For the actual shooting, see this, this, and especially this. Note that the ONG had worked itself into a very bad tactical location, with little place to retreat.

IN NO WAY DO I SUPPORT WHAT HAPPENED OR MAKE ANY EXCUSE FOR IT!!! It was FUBAR beyond all recognition, and I think it's a blotch on Ohio that the shooters were never brought to trial -- and I feel that way about Jackson State as well (and always have).