At least 27 dead in suicide attacks in northern Nigeria
Authorities attributed the attacks, which took place almost simultaneously about 7 pm local time, to the terrorist organization Boko Haram.
Most of the casualties were caused by a woman who blew herself up in a local market in the area, according to the Daily Post newspaper.
At about the same time, another woman and a man detonated the explosives attached to their bodies in another area of Mandari, apparently close to a displaced persons camp.
The attack came only hours after the Nigerian government announced the launch of a special military force to track the Boko Haram leader's whereabouts.
Mandari is located about 30 kilometers from Maiduguri, the capital of Borno state and one of the cities frequently besieged by the aforementioned terrorist organization.
Five people were killed on Sunday in another attack on the outskirts of Maiduguri, and two other attacks in July also killed 13 people.
The Nigerian government has sent army chiefs to the country's north-east to fight Boko Haram, which has increased its attacks in the region after the military operations drove them out from the areas that they had occupied last year.
Boko Haram, which means "non-Islamic education is a sin" in local languages, struggles to establish an Islamic state in Nigeria, a country with a Muslim majority in the north and a Christian majority in the south.
The group gained international notoriety even before self-proclaiming a franchise of the Islamic State (IS) in Africa by declaring its own Islamic caliphate in northern Nigeria.
Since the police killed the then Boko Haram leader Mohamed Yusuf in 2009, the radicals have carried on a bloody campaign in which more than 20,000 people have been killed and about 1.9 million have been forced to flee their homes.