About 10 men armed with assault rifles and grenade launchers fired three grenades into Kapoh district hall in Pattani province early on Tuesday and exchanged fire with police, killing one Buddhist police officer and one Muslim defence volunteer before escaping, police said.
Hours later, two explosions rocked the region where more than 360 people have been killed since January after gunmen raided an army camp and killed four soldiers before escaping with about 300 M16 rifles.
"The raid was intended to harm officials," Pattani police chief Tannachareon Suvanno told state-run Radio Thailand.
The raid came a day after police arrested three Muslim religious students and charged them with conspiring to kill a Thai Buddhist student at a state university in Pattani over the weekend.
As police and soldiers secured the raided offices with military trucks and machine guns, a remote control bomb was triggered by a mobile phone but injured no one, police said.
Almost simultaneously, a bomb hidden in a motorcycle fuel tank exploded in a market in Narathiwat province, damaging a parked car, police said.
Attacks on symbols of the largely Buddhist central government, such as state buildings, and ambushes of security officers take place almost daily in the region near the border with predominantly Muslim Malaysia.
The government has used a range of tactics and made personnel changes - including sacking two defence ministers in a year - in a bid to quell unrest in the south, where most people are Muslim and speak Malay.