Two people were seriously injured when their minivan overturned on the 12th Street ramp from I-495 North shortly after 2:00 p.m.
Police say they were trapped inside the vehicle for approximately 45 minutes.
The two were transported to Christiana Hospital with serious injuries.
Across the highway, police were on the scene of an accident involving a school bus.
There were no students on the bus.
Traffic is slowed in both directions on I-495.