Connecticut had an assault rifle ban. Didn’t stop Lanza. He used a rifle that didn’t meet the restrictions of that law.
Connecticut had a waiting period for purchases. Didn’t stop Lanza. He stole his guns.
Connecticut had a ‘gun free zone’ law and policy for school. Didn’t stop Lanza.
Connecticut had a security perimeter. Lanza shot his way in.
Federal law forbids guns to the mentally ill. Lanza stole his guns.
What Connecticut didn’t have is a requirement for teachers and administrators to trained and equipped to protect their students. The teachers and the Principal did was brave, but useless: Unarmed, they put their bodies between the shooter and the children. After shooting them, the shooter proceeded to shoot the children.
Let the Teachers have guns. Improve their odds.