The attack happened at 10:40 am on a road linking Yaning village to Khok village in Tambon Juab of Joh I Rong district.
A unit of five troops was patrolling the road in a military vehicle when an unknown number of insurgents detonated the bomb with a mobile phone.
After the bomb, the two sides exchanged gunfire for about five minutes before the insurgents fled the scene.
The two troops suffered slight cuts caused by bomb shrapnel.