Law abiding citizens should have the ability to defend themselves and others in government buildings (of all types) against criminals that don't follow the rules.
Americans, left, right, and center should agree a law should exist that requires school faculty to purchase and become poficient with a non-lethal weapon and have it on their person at work. These weapons could include mace, pepper spray, tasers, rubber bullets, etc.
The law should be expanded to allow students above the age of 21 to become proficient with and carry said weapons (as well as visitors in government buildings).
As a side, anyone with authority to carry a cocealed weapon (firearm) anywhere else, should be able to do so in areas of their dewelling including on campuses (dorms,etc).