The incident occurred when the driver of the jeep lost control over the vehicle and it skidded off a kucha road into the canal, said Deputy Development Commissioner in-charge of Palamu, Mukul Kumar Pandey.
Pandey told newsmen that the vehicle was returning to Hydernagar of the district when the incident took place.
One body of a woman has been retrieved, he said.
Twelve passengers have swam ashore while massive search operation was launched to trace six others, he said adding that the divers have been pressed into service.
He said the vehicle have been fished out and details were being awaited.