> In areas with strict gun control but limited access to firearms, mass killings still happen with other modalities. A lot of things can effectively kill a bunch of human beings assembled in a restricted area: knives, machetes, bombs, trucks, etc..

If these things were as effective as suggested, why is it that in America, one of the prime examples of loose gun control, just about all the recent mass killings have been committed with guns?

The other modalities exist but they're less effective (knife/machete/truck) or are hard to manufacture and use (bombs).

To give an example in favour of reduced frequency/lethality, have a look at Australia. We just don't see many mass killings there.