An elderly woman and a 10-year-old girl carried the explosives used in the attack.
They detonated their devices at screening areas set up by security forces outside two sites where worshippers were gathering for prayers in the town of Damaturu, Col. Sani Kukasheka Usman said.
Police spokesman Gbadegesin Joshua Toyin had earlier said at least 12 people were killed in the blasts as well as the two attackers.
A day earlier, two simultaneous bombings ripped through a market in the city of Gombe, capital of neighboring Gombe state, killing at least 48 people and injuring 58 others, a Red Cross official said.
One of the blasts was caused by a female suicide bomber, the other by a bomb hidden at the market, the official said.
The deadly attacks struck a region where violence blamed on the Islamic militant group Boko Haram
has killed hundreds of people in recent weeks.
No group has so far claimed responsibility for the latest attacks. But Boko Haram terrorists have previously carried out suicide and bombing attacks on bus stations and markets in Gombe and other northern cities.
Damaturu, which is about 185 kilometers (115 miles) northeast of Gombe, has repeatedly found itself the target of attacks tied to Boko Haram in the past.
Earlier this week, gunmen barricaded a highway that links Damaturu to another town and killed more than 20 motorists, a lawmaker said.
Security forces responded immediately to Friday's blasts in Damaturu, and the situation is "currently under control," an army statement said.
"The Yobe State Governor, Ibrahim Geidam and the Chief of Army Staff, Major General Tukur Yusuf Buratai have (sympathized) with the victims and the people of the state and urged residents to stay calm and be security conscious at all times," it said.
Boko Haram, which has pledged allegiance to the Islamist extremist group ISIS
, appears to have intensified its campaign of brutal violence in northern and central Nigeria recently.
The Nigerian military has been unable to put a stop to the frequent raids and bombings.
Boko Haram has been leading a ruthless, deadly insurgency for more than a decade, pushing to bring an extreme version of Islamic law, or Sharia, to the masses.
The government of Nigerian President Muhammadu Buhari
-- who took office in May
, pledging to step up the fight against the terrorist group -- said recently it would be open to talks with the militants at some stage.