It is the fourth attack in a week in which at least 162 people have been killed, including four suicide bombers, as Boko Haram Islamic extremists appear to obey an Islamic State group order to step up attacks in the holy month of Ramadan.
Nigeria's homegrown extremist group became the IS group's West Africa franchise earlier this year.
In the most deadly attack, the militants targeted several mosques in Kukawa town on Wednesday, gunning down nearly 100 praying worshippers. Kukawa is 180 kilometers (110 miles) northeast of Maiduguri, the biggest city in the northeast.