Interesting info here: (doesn't look like they've updated for this recent one)
https://ballotpedia.org/United_States_school_shootings,_1990-present#School_shootings_by_regionThere are no recorded school shootings in Delaware, Idaho, Kansas, Massachusetts, Montana, New Hampshire, New Jersey, Rhode Island, South Dakota, West Virginia, and Wyoming from 1990 to the present.
The breakdown of regional gun violence in K-12 schools is as follows:
Midwest: 43 incidents of gun violence, which resulted in 26 fatalities and 65 injuries
Deadliest incident: Red Lake High School massacre on March 21, 2005, where 16-year-old Jeffrey Weise killed five fellow students, one teacher and a security guard before killing himself.
Northeast: 12 incidents of gun violence, which resulted in 38 fatalities and 21 injuries
Deadliest incident: Sandy Hook Elementary School massacre on December 14, 2012, where 20-year-old Adam Lanza killed 20 children and 6 adults before taking his own life.
South: 75 incidents of gun violence, which resulted in 47 fatalities and 126 injuries
Deadliest incident: Westside Middle School massacre on March 24, 1998, where 11-year-old Andrew Golden and 13-year-old MItchell Johnson killed five fellow students and injured ten others.
West: 55 incidents of gun violence, which resulted in 65 fatalities and 124 injuries
Deadliest incident: Columbine High School massacre on April 20, 1999, where 18-year-old Eric Harris and 17-year-old Dylan Klebold killed twelve students and one teacher, before turning the guns on themselves.
Also here:
http://lawcenter.giffords.org/gun-laws/policy-areas/guns-in-public/guns-in-schools/These states allow CCW or have no law against carrying:
Alabama - Number of incidents: 3 Number of injuries: 1 Number of fatalities: 1
Alaska - Number of incidents: 2 Number of injuries: 3 Number of fatalities: 2
Hawaii - Number of incidents: 2 Number of injuries: 2 Number of fatailties: 0
New Hampshire - Number of incidents: 0 Number of injuries: 0 Number of fatalities: 0
Oregon - Number of incidents: 7 Number of injuries: 32 Number of fatalities: 6
Rhode Island - Number of incidents: 0 Number of injuries: 0 Number of fatalities: 0
Utah - Number of incidents: 2 Number of injuries: 2 Number of fatalities: 0
Wyoming - Number of incidents: 0 Number of injuries: 0 Number of fatalities: 0
Other than Oregon it looks like those states have it under control
California leads the way with most incidents, followed by Florida