More than 10 armed and masked men raided a local administrative office in Pattani province on Friday night, tying up officials before setting the building ablaze and fleeing.
Initial reports said the attackers, dressed in black and carrying military-style firearms, entered the Sakon Bon Sub-district Administrative Organisation office, in Mayo district, at about 7.30pm.
Five people, including security guards and garbage collectors, were still on the premises after finishing their duties when the attackers arrived.
The group split into four teams, with one positioned at the front of the building while another rounded up the five people and tied their hands.
A third group set fire to a garbage truck, causing minor damage to the vehicle. The fourth group entered the office building, allegedly poured fuel throughout the premises and set it alight, causing extensive damage.
All the attackers then escaped through the same rear entrance by which they had entered.
Officials and local residents initially tried to contain the blaze, before firefighters arrived and brought it under control after about 30 minutes.
No one was injured, although the security guards and garbage collectors were left badly shaken.
Security forces remained deployed around the building on Saturday morning and sealed off the surrounding area amid concerns that the attackers may have left explosive devices behind.
An inspection found that the second floor of the building had been extensively damaged. The ceiling, walls and much of the interior were blackened by smoke, while windows were shattered.
Furniture, documents, electrical equipment and other government property was also damaged. The extent of the losses is still being assessed.
The attack was among several incidents, including setting tyres on fire, reported in Pattani on Friday night.
