The incident occured last evening when the car, in which B N Mishra was travelling along with his family, lost control in a bid to save a cyclist and plunged into the pond near Chakwa village, they said.
While Mishra, his wife Nisha and son Sachin were rescued by the local residents, Honey (5), Shivani (3) and Shivam (17) drowned, police said.
Body of Shivam has been fished out and efforts were being made to trace bodies of Honey and Shivani, they said.