The bomb went off on a local road in Ban Aipayae of Cho Airong district about 8am.
Deputy Narathiwat police chief Pol Col Manas Sigsamat, who led a team of reinforcements and bomb disposal experts to the scene, said the explosion left a crater two metres deep and three metres wide in the road. The armoured vehicle was lifted into the air by the blast, and its rear wheels fell into the crater, stranding the vehicle.
The injured rangers were named as:1. Sgt Abdulrohim Yama, leader of the patrol team2. Ranger Tangpong Phapan3. Somchai Watwongpan4. Ranger Sornchai Chandaeng5. Ranger Chuwit Chanthip, and 6. Ranger Amornsak Kwanruan
Sgt Abdulrohim told police that he was leading the rangers patrol on the road in the armoured car when a bomb estimated to contain 50kg of explosive contained inside a cooking gas cylinder and buried under the road surface was detonated.
The attackers hiding in roadside forest then opened fire at the rangers. Sgt Abdulrohim had ordered his teammates to crawl out of the armoured car and fire back, while radioing for reinforcements from police and soldiers in Cho Airong.
The attackers fled the scene after about a 15-minute fight, he added.
Police blamed separatist militants for the attack.
Education Minister Pongthep Thep Kanchana said on Friday that the prime minister, who had visited the deep South on Thursday, had directed security units there to come up with more stringent security measures for government teachers, who have closed schools in fear of their lives and demanded better protection.
The teachers will be provided with protection from their residences until they arrive at their schools, particularly those in risk areas, he said.
Mr Pongthep said he expected teachers would feel reassured and reopen all state schools in the southernmost provinces on Monday.
Schools in the far South have been closed since Wednesday, after several teachers were killed in recent attacks.
The minister said a committee had been set up to consider providing fair and just compensation for teachers killed or injured in the South. A decision was expected within a month.