The accident on Monday evening also left three others injured.
Superintendent of Police Omveer Singh said the truck driver tried to flee from the spot but was chased by locals and handed over to the police.
The deceased have been identified as Mannu Gaur (19), Gulshan (13) and Akhilesh Yadav (25).
The bodies of the deceased will be sent for postmortem, police said.
A case has been registered against the truck driver under sections 105 (punishment for culpable homicide not amounting to murder) and 324(5) (whoever commits mischief and thereby causes loss or damage to the amount of one lakh rupees or upwards) of the BNS. PTI COR NAV DV DV