Pattani police were informed of the incident at around 11am where a food shop near a coffee shop and restaurant named Bigben in Pattani municipality was hit by bomb attacks.
One defence volunteer was killed at the scene while the other two were pronounced dead at Pattani Hospital. Nearly 10 residents were also wounded from the bombing, including one defence volunteer.
The impact of the explosion damaged the two storey Bigben coffee shop and restaurant as well as nearby shops while many motorcycles parked near the area were damaged.
According to an initial investigation, the three defence volunteers were on duty at the roundabout as part of security measures following the series of bomb attacks and arsons in the province since Saturday evening.
They were around five metre away from the bombs.
The police determined that the assailants built the homemade bombs inside the fire extinguisher cylinders and placed the bombs at the scene.
Police said that one bomb has completely exploded but another one was partially working and was defused by experts.
Prime Minister Yingluck Shinawatra said that she has received reports about the explosions and arsons in Pattani.
She has expressed worry over the safety of residents and security personnel working in the province and asked the security agencies to provide safety for residents.
However, she declined to say if the series of attacks in Pattani were retaliation by an insurgent group after 16 militants were killed while they were attacking the military base in Narathiwat last week.
She said this was a sensitive issue and the Operations Centre of the Committee to Mobilize Policy and Strategy to Solve Problems in the Southern Border Provinces would be assigned to brief the situation to the public.