It happened around 4:00 Tuesday afternoon on the off ramp of Route 141 north, going toward Market Street.
Police say a male driver was behind the wheel of a pickup truck when the vehicle's brakes failed.
The pickup ran into the back of a dump truck.
Both the driver and his passenger were trapped and had to be extricated from the vehicle. They were taken to Christiana Care Hospital for treatment.
The female passenger is listed in stable condition and the driver is undergoing tests for head injuries.
No other injuries were reported.