The debate will continue to rage on because of this horrible event.
But when people say how "easy" it is to get firearms in the US, I would swear those people are ridiculously underinformed of how much a person has to go through to legally own a firearm, let alone carry one in public (depending on the state things may even be harder). Now registered, lawful firearm owners are the least likely people to carry out violent crimes involving firearms. There are incidents of people being harmed with legally owned firearms, sometimes children. Those incidents are varied from accidental discharges to incompetence, and sometimes yes crimes are committed.
However the people most likely to commit a violent crime with a firearm, involving a discharge and injury or death are people who do not own them legally. How is more regulation of legally owned firearms going to stop criminals from being criminals?
And yeah you could just take everyone's right to firearms away, punish folks who have done and more than likely will never do a thing wrong/unlawful with those firearms. It won't stop criminals from illegally obtaining guns. Not in a country this size, with as many unsecured access points. It will only harm the folks who follow the laws as is.
Education is the best way of preventing crimes, and a better mental health system that doesn't stigmatize the people who need the help and actively seek it. I'm one to readily admit to being bipolar, and having other unresolved mental health issues but dammit if I don't get a lot of fucked up looks from people like I'm going to go on a shooting spree.
I wouldn't. I'm a diplomat and pacifist up to a point, until all other avenues of conflict resolution have failed and I'm backed up against a wall or in a corner. I'd never resort to violence as an answer or solution, only a last ditch effort to prevent the loss of life.
There's no clear answer on how to prevent mass killings, but I could guarantee it wouldn't be taking everyone's right to bear arms away.