The incident happened near Titiha bridge close to Haldikhoda More on National Highway (Extension) - 327 which runs from Araria to Bahadurganj in Kishanganj.
Bahadurganj Station House Officer (SHO) C P Yadav said the mishap happened when the driver of the tractor lost balance of the vehicle, which overturned killing the two persons on the spot.
"We are trying to ascertain the identity of the two deceased. The four injured persons have been sent to Araria for treatment. Jokihat police station in Araria has also been informed about the mishap," Yadav added.