The source of the fire which broke out at around 07.00 p.m. local time is still unknown, Chief of the Dumai City Disaster Mitigation Board Tengku Ismet said.
No fatalities or injuries were reported.
However, the fire is believed to have burnt important documents and office appliances including a motorcycle.
Ismet said the city fire department had sent four fire trucks to the scene and the blaze could be put out more than one hour later.
"The fire could be extinguished one hour after it broke out but all the contents of the building have been burnt. It is believed the fire was caused by a short circuit," he said.