This tells me several things:
1. Someone near here was out hunting. The markings on the cases indicate the brand of ammo was Federal. In .30-06, this brand runs about $35 to $45 per box of 20. Most people won't go firing off $10 worth of ammo unless they're aiming at something.
2. Someone near here was hunting from the roadway, which is illegal just about everywhere. In Nebraska, it's a Class III misdemeanor.
3. Someone near here was hunting out of season. Deer season here starts November 14th. In Nebraska this is a Class III misdemeanor.
4. Someone near here is a really lousy shot. Assuming they were using a legal firearm, they discharged their entire magazine. (NE law prohibits deer hunting with a rifle with greater than 6 round capacity)