We would like you to assess the QUALITY of each of the following argument (discussing Gun Control) and determine if the argument is Valid or Invalid. A valid argument is clearly interpretable and either expresses an argument, or a premise or a conclusion that can be used in an argument for the topic of gun control. An invalid argument is a phrase that cannot be interpreted as an argument or not on the topic of gun control.

As far as I am aware, hand guns are illegal outside of the military and police since the Dunblande massacre when a man walked into a school in 1996 and shot a class of children and their teacher.
Valid

Countries that ban guns or implement stricter laws concerning firearms have lower crime rates.
Valid

The difference is the fact that at the time firearms were not prohibited on school grounds which lead to return fire coming from regular citizens and students in aid of the police on the scene.

Valid