The mishap last night happened when the workers in the tractor-trolley were returning to Nehtaur village from Chandpur where they were taken for work by a contractor, police said.
The collision of the tractor with the sugar bags-laden truck was so fierce that both the vehicles overturned into a roadside ditch after the accident, police said.
According to statements of those injured, the number of those dead was nine, out of which six bodies were recovered by the police while another three are still lying under the overturned vehicles at the accident site.