The Army said it was battling to save lives of 19 other soldiers injured during the clash on Thursday.
Operatives of Civilian-JTF, embedded with the military squad, were also badly injured in the deadly encounter in a village called Nguro Gongon.
Spokesman of Nigeria army, Sani Usman, said the injured soldiers have been evacuated to Maiduguri the Borno State capital, while a rescue team was deployed to go searching for the missing soldiers.
Usman, a colonel and acting director of army public relations, said:
“Today morning, troops on clearance patrol at Guro Gongon village and environs to rout out remnants of Boko Haram terrorists hibernating therein, destroyed the terrorists’ makeshift camps and recovered quite a number of weapons, equipment and foodstuff in the process.
“The recovered items include 1 Gun truck mounted with an Anti-Aircraft Gun, a MOWAG Armoured Personnel Carrier (APC), 1 Rocket Propelled Grenade Tube, 1 Light Machine Gun, 3 AK-47 rifles and motorcycles.
“However, the gallant soldiers basking on the recorded success, returning to their defensive locations, ran into an ambush by a group of Boko Haram terrorists who came to reinforce their fleeing comrades. The troops fought back gallantly killing several of the insurgents.
“Sadly however, 19 soldiers and 3 civilian JTF members were wounded in action while a few others were missing in action.
“The wounded have been evacuated and are responding to treatment, while a search and rescue party comprising of Special Forces personnel has since been dispatched to establish contact with the missing in action troops, some of whom, as at the time of filing this report, have started returning to their defensive location.
“It is pertinent to state that, no stone would be left unturned until every person involved in the operation has been accounted for,” he said.