You cannot secure the campus. Too large.
Yes you can, by calling on State police and the local town police.
That place is 4x’s bigger than our nearest town..Can’t secure something like that,,just arm it..
The question to be raised it how many of those students arrived for class after the first shooting, and were shot. You can certainly turn away traffic at the entrances, and use email / phone tree technology to inform people in short order that something is amiss.