The police said the accident occurred at Dadar village in Mohania police station last night when a jeep collided head-on with a bus.
"All the dead and injured were traveling in the jeep from Mohania to Asrari village some distance away. The bus was Bhabhua-bound and was coming from Patna," Mohania Station House Officer (SHO) R P Yadav said.
The deceased have been identified as Basawan Ram, Mohammad Haider, Ramdayal Ram and Gyani Ram.
The SHO said the injured were first taken to the sub-divisional hospital and then referred to Varanasi for better treatment. The bus and the jeep have been seized, while the dead bodies have been sent for postmortem.