Police officials said the incident happened near Shambhubigha village under Dehri police station, and the driver has been identified as Sanjay Ram.
Dehri Station House Officer (SHO) Sanjit Kumar Sinha said the tractor belonged to one Om Prakash Tiwary of Patanwa village in Indrapuri police station area.
"Ram had taken the tractor to Sasaram town for servicing and was returning with it to Patanwa, when unidentified persons ambushed and killed him with sharp weapons. They then fled away with the tractor," the SHO said.