Not the only place this happens. Violence happens across the globe. Mass murders happen across the globe on a daily basis, firearm or not.

The UK and Australia saw an increase in knife crime when they began heavily regulating/banning firearms and are still dealing with higher instances of knife related violence. The US will see a similar spike if similar regulations are followed without addressing the underlying reason for the violence, firearm usage or not. The US currently sees more murders from knives than rifles, as it already is, for example. See FBI crime statistics from nearly any recent year. This is 2017 which is when the US had its worst mass shooting in Las Vegas, NV. ucr.fbi.gov/crime-in-the-u.s/2017/…/table-20 but still shows this.

No one is saying “no way to prevent this”, we just have different ideas of what would prevent/reduce this.