I met a guy from Northfield, Minnesota a few years back. He told me that they're still talking about the robbery. It was, apparently, the ONLY thing that ever happened there.
There are two good colleges in Northfield, St.Olaf's and Carleton, and it's a pretty area, but you're probably correct. They haven't had anything like that happen before or since. It's about one hundred miles from where I live, but it's a nice stop on the way to the Twin Cities.