The Brief The Milwaukee County Sheriff's Office shut down I-43 northbound on Friday. WisDOT reported an "incident" near Fond du Lac Avenue. The Milwaukee County Sheriff's Office shut down I-43 northbound near Fond du Lac Avenue on Friday night "due to an incident." Wisconsin Department of Transportation cameras showed significant traffic backups, with all vehicles being diverted off the interstate. The incident happened at around 7:30 p.m.