According to the BBC:
US President Donald Trump has said arming teachers could prevent school shootings like that which left 17 people dead last week in Florida.
A staff member with a gun could end an attack "very quickly", he said.
Similar to this question but not opinion based (so hoping it won't get closed), I'm wondering is there any data supporting or refuting the effectiveness of arming teachers as a way to prevent or reduce the severity of gun violence at schools? I'm also wondering how the effectiveness of arming teachers compares to the effectiveness of other approaches to reduce school gun violence, such as gun control legislation.
Note I don't see this as a duplicate of What is the value of armed bystanders in preventing gun deaths? as I'm specifically asking for data about teachers.