A Greyhound bus carrying 80 passengers left Interstate 39/90/94 at mile marker 135 on the northeast side of Madison and plowed though a fence Friday afternoon, snarling eastbound traffic on the Interstate, the Wisconsin State Patrol reported.

The State Patrol said the city of Madison was sending buses to the site to pick up passengers. Police said eight to 12 people were reportedly injured, and several ambulances have been dispatched.

The State Patrol is investigating the cause of the crash.