The incident occured when the driver of the overcrowded tractor trolley lost control over the vehicle due to high speed, they said.
Suraj (7), Rambhu (10), Raja Babu (14), and Sunil (19) from Madhopur village were killed on the spot when the truck was imbalanced and overturned in Bansi Kotwali area in the district.
The bodies of the deceased have been sent for post mortem and the injured have been admitted to a nearby hospital, police added.