- Tag results for Boko Haram
Buhari, who headed a military government in the 1980s, was seen as a better bet to end the violence, which has killed at least 20,000 since 2009.
Nigerian forces battling Boko Haram jihadists need a change of mindset to overcome an evolving guerrilla threat, US military officials said this week on the sidelines of an African security summit.
Nigeria is one of just three countries where polio is endemic and has not been eliminated, along with Pakistan and Afghanistan.
Boko Haram fighters attacked a military base in the Cashew Plantation area at the entrance to the city with suicide bombers, mortars and guns, leading to a prolonged battle.
The suspected Boko Haram attack took place late Friday in the northeast Borno state capital of Maiduguri, the epicentre of the group's Islamist insurgency.
A local official on Sunday confirmed the toll of "five dead, all civilians", adding that several were also wounded in the attack.
Describing the release of the 107 youngsters -- 105 schoolgirls and a younger boy and girl -- as a "cheery and hearty" development, Buhari pledged to recover "every abducted citizen in Nigeria."
A total of 104 of the 110 students seized from the school in Dapchi, in the northeastern state of Yobe, on February 19 were dropped off by the Islamist militants on Wednesday morning.
The Islamists who kidnapped 110 schoolgirls in Dapchi, northeast Nigeria, just over a month ago have so far returned 101 of the students to the town, the government said on Wednesday.
A senior government source in Abuja and police in Yobe state also confirmed the girls' return although it was not immediately clear how many of the 110 students had been freed.
MSF and the UN pulled out their staff from Rann, on the border with Cameroon in Borno state, after the attack on March 1.
The disappearance of the students from Dapchi on February 19 also threatens access to education for girls in a region already plagued by low levels of school attendance.
Those killed were Nigerians working for the International Organization for Migration and the UN children's fund Unicef.
Heavily armed Islamist militants abducted 110 girls from their school in Dapchi, in Yobe state, northeast Nigeria, on February 19.
The attack happened "after dark" outside a camp housing some 55,000 people displaced by the conflict and appeared to target the military.