I also can't guarantee they won't get diabetes or heart disease, or fall off a ladder, or be hit by one of the passing cars. All of which are vastly more likely to happen than being shot, which itself is an order of magnitude more likely than an innocent person being shot. (ie, not robbing a drug dealer, etc)
Dead is dead, and a car gets you there just as quickly. Focusing on one is silly. (Unless you're a crossing-guard, for instance.)
I normally see the irrational fear (crypto-racism) argument from people who want to limit refugees. You've got a higher chance of dying from someone falling off a ladder onto you than being killed by a terrorist hiding as a refugee. I'm not saying you're a crypto-racist, I'm saying this sloppy thinking is used to support other nonsense arguments because it's so empty you can use it to support anything.