The crash happened before 6:30 a.m. Tuesday near the Delaware Memorial Bridge.
It was not immediately clear what led to the collision. Police say one of the vehicles rolled over several times.
Medics took one person to Christiana Hospital with injuries described as non-life threatening.
Southbound vehicles exiting the Delaware Memorial Bridge toll plaza were diverted onto Route 9 for more than an hour as crews worked to clear the wreckage.
Traffic was flowing normally again by 9 a.m.