One solution

Here's what happened in Florida. According to a  Sun Sentinel article by Skyler Swisher, the killer,

"fired more than 100 rounds in a roughly three-minute span, killing 17 and wounding 15 others."

Right after the incident, there was the usual hand-wringing. What can be done? Why is this happening?' 

Gun rights advocates say, of course, its not the gun but the wielder of the gun who is at fault. In this case, however, it wasn't a handgun, it was a high-powered rifle that could fire 100 rounds in three minutes.

Here's a partial solution to a complex issue. Ban the AR-15, the weapon Cruz used. Make it as difficult as possible to obtain weapons that can fire that many rounds that quickly because it isn't a defense weapon.

No one fires that many rounds to defend themselves unless they are in a war.