The Fourth Army Area said the patrol was ambushed at 9am on Highway 418 in Tambon Borthong of Pattani’s Nongchik district.
The bomb was detonated by an unknown number of assailants as the five rangers passed in a six-wheel truck on the way to their Ingkhayut Borihan base.
The injured soldiers were identified as Surasak Urairak, Thira Limpasakul, Krithapol Prompradu, Piyanat Phanduang and Khirirat Tintachart. They were rushed to a field hospital at the base but none suffered life-threatening injuries.
The bomb was hidden under a pile of dirt left by road repairs.
Fourth Army Area commander Lt-General Kriangkrai Srilak ordered an investigation at the scene in a bid to catch the assailants.
He said the explosion was an attempt to create unrest in the deep South.