The landmine blast happened in the northeastern state of Borno, where security forces have been battling Boko Haram militants for more than a decade.
Nigeria faces a raft of security challenges including a long-running insurgency by Boko Haram in the northeast, separatist violence in the southeast, rampant oil theft in the Niger Delta and kidnapping for ransom by criminal gangs in many parts of the country.
Shaibu Musa, a local vigilante officer helping security forces to combat the insurgents, said a military vehicle was travelling along the road linking the villages of Monguno and Baga on Thursday when the vehicle detonated an improvised explosive device.
The military did not immediately respond to request for comment on the incident.
Another security official, Isa Bukar, said the explosion occurred after soldiers on patrol triggered the mine, which killed seven of them.
