Damages were estimated at 60 million baht following a bomb attack at Super Department Store on Chamroon Nara Road in Muang district's municipal area. It also caused 200 workers to lose their jobs.
The blast happened in an area authorities had declared as a "safe zone" _ an area with tight security and several checkpoints.
The store and its branches in the three southernmost provinces of Narathiwat, Yala and Pattani have been the targets of 17 bomb and arson attacks since 2004 when insurgent violence flared up in the region, said Waraporn Sirichai, deputy managing director of the store.
"The entire family was on their knees when we got a phone call from our staff on Friday. We all screamed, 'Not again."' she said.
Ms Waraporn said she had examined the fire-gutted building and estimated the damage at about 60 million baht. The goods were almost completely destroyed.
Mrs Waraporn called on the government to provide prompt compensation.
"I really have no idea what kind of compensation will be offered. I want them to act fast. We have employees to take care of," she said.
Businesses seem to be a favoured target of insurgent activity in Muang Narathiwat municipality.
Pol Col Satanfah Wamasingh, investigating superintendent at Muang police station, said Friday's blast is likely to be the work of the same group that plotted a coordinated series of bombings last year that killed seven people.
On Oct 23, two explosions took place in Narathiwat's Muang district's municipal area, about 10 minutes apart: one at the four-storey Jintai Junior convenience store on Phichit Bamrung Road and the other at the two-storey Sui Hua Panich convenience store on Chamroon Nara Road.
He said that it was highly likely that the assailants disguised themselves as customers and planted the bomb.
Yulaipa Nima, a staff supervisor at Super Department Store, said yesterday that the incident had left her shattered.
"It is hard enough to live in fear of insurgent attacks. Now I am technically jobless," she said.
She reiterated a call for the government to help the workers quickly as they faced the prospect of unemployment.
The fire was not completely extinguished when Thakoengsak Yoksiri, chief of Muang district, rushed to the scene at 7am yesterday.
Mr Thakoengsak said the one-storey building was almost totally destroyed by the fire.
It would take some time for police and forensic investigators to sift through the charred debris for evidence.
He said a five kilogramme bomb with fuel attached to it was the likely cause of the explosion.
Pol Col Satanfah said investigators were reviewing surveillance cameras installed outside the department store and at security checkpoints to look for vehicles that might have been used in the attack.
The bomb blast topped off multiple insurgent activities in the restive South on Friday which were seen as a gesture to mark the 50th anniversary of Malaysia's independence from British rule and the anniversary of the founding of the Bersatu separatist movement.
National Security Council (NSC) secretary Wichean Potephosree, who was sent by Prime Minister Yingluck Shinawatra to the troubled region, said yesterday the multiple attacks were an attempted show of power and strength.
"Their message is that they are still here and capable," Pol Gen Wichean said.
He insisted that intelligence operations had not failed.
Authorities learned that insurgent acts would happen, but did not know what form they would take.
He said security operations in the safety zones were better integrated but were hampered by a shortage of personnel. Pol Gen Wichean said the NSC is still pursuing its policy of holding peace talks but that the process has been "stalled from time to time".