Solving problems with a gun

Three people were shot at a Jewish museum in Brussels, six near Santa Barbara, California. We know almost nothing of the two assassins in Brussels, but we know a good deal about the young man who committed the murders in California. He was rejected by girls, he was unhappy, so he bought a gun, in fact he had a number of guns, and thought that by killing people he would solve his problems. We can surmise that the gunmen in Brussels thought that by killing three tourists and seriously wounding a fourth they would contribute to the solution of the problems of the Middle East. It is impossible to fathom the thinking of people. The assumption that people act rationally certainly doesn't hold. Yet dismissing these killers as crazy is an easy way out. In both instances the killers were guns. Guns have no business being in the hands of  unauthorized people in the community. Americans have a love of guns that people outside the United States can't understand, but where did the gunmen in Brussels obtain their weapons? Did some armed organization put them up to it, making use of two gullible individuals to commit senseless murder? The Californian young man is dead, killed in the exchange of fire, so his problems are solved even if not in a satisfactory manner, one of the killers in Brussels has been apprehended, the other is still on the run, but the problems of the Middle East are no nearer to solution. Their action just confirmed that the hatred of Jews is widespread, something that needed no confirmation.