The mishap occurred around 9 AM between Sarsina and Khatoli villages. Since the car was locked from inside, the passengers could not be rescued in time," Superintendent of Police (Rural) Jagdeesh Sharma said.
Three persons died on the spot and another succumbed to injuries on the way to a hospital, he said.
The deceased have not been identified yet and the number of the car could not be ascertained as the plate has been burnt, the SP said.
The dumper was engaged in highway construction work, he said, adding the driver fled the spot.