Pol Lt Surachai Waditsuphaphol of the Phuket City Police was informed of the at about 10am.
Officers and four fire trucks from Ratsada Municipality soon arrived at the scene, at the municipality office on Ratsada Nusorn Rd in Moo 3, Ratsada, to find smoke billowing from the first floor of the building.
All people in the building had been evacuated to safety, and firefighters too 45 minutes to bring douse the blaze.
Ratsada Mayor Nakarin Yosaengrat said he was upstair in his office when he heard the alarm, at about 9:45am.
A municipality staffer had arrived at work only to find smoke filling up the room, but was unable to find the source of the fire, Mayor Nakarin said.
Municipality workers cut off electricity supply to the building and the fire department was called, he added.
At this stage the cause of the fire is believed to had been an electrical short circuit, Mayor Makarin noted.
Documents were destroyed in the fire and the ceiling of the room suffered damage, he confirmed.
Exactly which documents had been destroyed have yet to be confirmed.