An unidentified group has set an excavator, which was being used for mining the stone from a quarry in Byas Municipality-11, on fire on December 21. The excavator bearing the plate number Ga 1 ka 3441 belonged to Bhairav Construction Service Private Limited. The Construction Service is planning to file a complaint on December 23.  The cabin of the excavator has been completely destroyed by fire. The perpetrators and their motive for arson have not been identified said DSP Lilaraj Lamichanne.