One bomber blew up inside the mosque and the second waited outside to detionate as survivors tried to escape, said coordinator Abba Aji of the civilian self-defense Vigilante Group.
At least 17 people were wounded and evacuated to the hospital, said Abdul Mohammed of the State Emergency Management Agency.
Umar Usman said he escaped because he was late. "We were just a few meters away from the mosque when a loud bang erupted and all we could see was dark smoke and bodies littered around," he told The Associated Press.
Several suicide bombers have exploded in recent months at roadblocks leading into the city manned by the military and vigilantes, indicating success in preventing attackers from reaching crowded areas.
It is the first attack on Maiduguri since December 28, when Boko Haram attacked with rocket-propelled grenades and multiple suicide bombers, killing at least 50 people.