Mahato who was injured following the incident died in course of treatment at the Bharatpur Medical College, police said.
The accident took place at around 2:00 am this morning, as the tractor was heading towards the west.
The tractor, without any registration number and the driver has been taken into police custody.
Meanwhile, one person died and 23 were injured when a passenger bus hit a stationary truck at Basamadhi-2 on the East-West highway.
The bus was going towards Pokhara from Birgunj at the time of the accident.
The name and address of the deceased is not known. His physical features look like he is of Tarai descent. The site of the accident is eight kilometers to the west of Hetaunda.
Police said the man died while being taken to hospital. The bus driver and conductor have sustained serious injuries.
Eleven of the passengers who were injured in the accident have been sent to Bharatpur while the rest of them are receiving treatment at Hetaunda hospital.
When will it end?