Authorities say suspected sect members have killed four people in three separate attacks in the country's northeast.
Military spokesman Lt. Col. Hassan Mohammed said Thursday that two gunmen shot dead a prison guard in a barber shop alongside the shop's owner in the city of Maiduguri Wednesday evening.
He said a civilian was also killed hours earlier a few miles away and another was shot dead minutes after the barber shop attack Wednesday.
Borno State police chief Simeone Midenda said police suspect the same Boko Haram members carried out the three attacks.
Boko Haram is a radical Muslim sect responsible for a string of assassinations and bombings in northern Nigeria in its campaign to implement strict Shariah law in Africa's most populous nation.