The arson occurred when activists of agitating Mizo Zirlai Pawl (MZP) or Mizo Students Federation tried to storm the deputy commissioner's office, Champhai Sadar SDO Pachhunga told PTI.
The persons responsible for the arson were yet to be identified.
Several persons were injured when the police tried to disperse the agitators from near the DC's office, he said.
MZP launched an agitation from Tuesday demanding posting of more doctors in Champhai District Hospital.