The attack occurred about 50 minutes after midnight when 20 paramilitary rangers were returning from guarding the annual Pattani Red Cross Fair. They were travelling in a pick-up truck and a six-wheel truck, heading to their base in Nongchik district.
The two trucks stopped at the stop sign of the Don Rak intersection, which links to the Pattani-Hat Yai highway.
Police said the two trucks were waiting to turn on to the highway when insurgents detonated the bomb with a walkie-talkie.
The insurgents, who were hiding in bushes at the roadside, opened fire at the paramilitary rangers and the two sides exchanged gunfire for about five minutes before the insurgents retreated.
The two trucks were slightly damaged by the bomb shrapnel. The 16 paramilitary rangers, 10 of whom were women, were slightly injured and sent to the Pattani Hospital.
Security agencies had earlier learned that insurgents would try to attack the Red Cross fair and had thus beefed up security at the fair. Police believe insurgents changed their target to ambush the security officials on the way from the fair instead.