The assault happened in Illinois, which is a heavy-gun-control state. The perps drove in from Indiana.
Notice two of them were from Bloomington? That's the home of Indiana University, which has had rep for harboring Reds and the mega-pervert Kinsey, going all the way back to the 1930's. Very, very Red schoolhouse.
You could get, and can still get, an education there -- my godfather attended, in the late 30's, and they didn't faze him.
But it's significant that those guys were from down there -- they weren't just over the line in Hammond or something.