Three blasts struck a mosque and the area near the building in the northeastern Nigerian city of Maiduguri, a military spokesman said on Sunday.
A hospital source, speaking on condition of anonymity, said at least eight dead bodies had been recovered from the area, with many more feared dead, and around 50 injured people had been taken to hospital for treatment.
There was no immediate claim of responsibility for the explosions on the edge of the city centre but they bore the hallmarks of Islamist militant group Boko Haram.
Maiduguri, the state capital of Borno, is the birthplace of the jihadist sect which has waged a six-year insurgency in its bid to set up a state in the northeast of Africa's most populous nation adhering to strict Islamic laws.
"There were three improvised explosive devices explosions at Gomari and Ajilari general area in Maiduguri at about 7:21 p.m. [1821 GMT]," said military spokesman Colonel Sani Usman.
"Although details are not clear, it is important to note the attacks signify high level of desperation on the part of the Boko Haram terrorists," he added.
Bubakar Aliyu, a farmer who had just finished praying at a smaller mosque, said, "I heard the first blast from the main mosque ... another exploded at a cluster of shops. I ran back to home and as I approached my house I heard another blast."
Suspected members of Boko Haram have killed around 800 people in Africa's most populous nation in a spate of bombings and shootings since President Muhammadu Buhari's inauguration on May 29, according to a Reuters tally.
A new audio message purportedly from Boko Haram leader Abubakar Shekau, which was released on social media on Saturday, calls the Nigerian army liars for saying troops have regained territory from the militant Islamist group.