No, its not hail.  Nor is it one of the ten plagues. Its kids with nothing better to do.  According to police, a foursome (perfect for a golf outing), took out their frustration on a local middle school in Duluth, Minnesota, by pelting it with golf balls.

Coincidentally, the school sits next to the Northland Country Club's golf course and it appears that the ruffians launched the golf balls from there resulting in the damage to eight windows and 10K in vandalism.