The seven persons were returning to their native villages in Khagaria district after attending a marriage ceremony at Bakhri in neighbouring Begusarai district, Gangaur Police Station SHO Gajendra Kumar said.
The incident took place on Khagaria-Bakhri road near Pahraja after the driver dozed off, lost control of the four-wheeler and hit the tree, the SHO said.
The deceased have been identified as Dipak Kumar (21), the driver of the vehicle and Sanjiv Kumar (28), the SHO said.