The accident happened just before 6:00 a.m. Wednesday at the intersection of Route 206 and Flyatt Road in Tabernacle Township.
The dump truck and one of the cars careened off the road and into a wooded area.
The driver of the dump truck sustained a head injury. One of the other drivers suffered a neck injury and a third person suffered unspecified injuries. All three were transported to an area hospital for treatment.
HAZMAT crews are still on scene mopping the diesel fuel spill from the dump truck, in an effort to contain any environmental impact.
it is unclear how many gallons of diesel fuel have leaked.
Drivers should expect traffic detours during the cleanup.