According to police, a Chevrolet van carrying several passengers was trying to get to the shoulder of the road. Witnesses said a semi-truck just behind it was weaving on the road. The semi hit the van, causing it to flip over.
Two passengers inside the van were killed, and 16 others were injured, some critically.
The truck driver also sustained minor injuries.
There were unconfirmed reports Sunday evening that all the van passengers were from Chicago.
Police had not released the names of the victims Sunday night.