Twenty paramilitary troops from Ranger Company 4603 in Narathiwat on three armoured vehicles were on the way to support the search operation when they were attacked at Cho Airong district.
Two rangers wee killed while an other three were wounded and sent to hospital.
Police inspected the scene and found explosive fragments scattered around the area. The 20 kg homemade bomb was built into a gas cylinder and triggered by using a radio signal.
In separate developments, Narathiwat police inspected sites of multiple attacks in four districts -- Yi-ngo, Bacho, Ra-ngae and Rueso.
The attacks included arson at a roadside rest area (a sala or pavillion), a hospital and local government office; and throwing bombs at a military base.
A numberof ATM booths of commercial banks in the province were also bombed early today.
The suspected insurgents also bombed ATM booths in Yala, Pattani and Songkhla in the same timeframe.
The authorities believed that the assailants tried to cause disturbances rather than to take lives or money as the ATMs were damaged but cash was not taken.