This level of fear you describe is not a healthy or reasonable way to live your life and is not a very typical sentiment. A professional can help you figure out where these feelings are coming from and what you can do to manage them.
Sure, there are crazy and violent people out there, I don't deny that.
I know I was being somewhat of an urbanist zealot in my last comment, but for real...regardless of whether you prefer suburbs and spending more time in your car or the city and spending more time on foot, this isn't a healthy way for you to see the world in either case.