Two young girls approximately seven or eight years old blew themselves up in a northeastern Nigerian market on Sunday, killing themselves and one other person and wounding 18 others, sources said.
The girls were "seven or eight", a local militia member in Maiduguri, Abdulkarim Jabo, told AFP.
The attack was not immediately claimed by Boko Haram but bore the hallmarks of the jihadists, who routinely use women and girls to carry out suicide attacks, often in Borno state, the epicentre of their insurgency.
Borno Governor Kashim Shettima, visiting victims in the hospital, confirmed the toll in the attack.
Maiduguri militiaman Jabo said he saw the girls on Sunday immediately before the explosion.
"They got out of a rickshaw and walked right in front of me without showing the slightest sign of emotion," he said.
"I tried to speak with one of them, in Hausa and in English, but she didn't answer. I thought they were looking for their mother," he added. "She headed toward the poultry sellers, and then detonated her explosives belt."
Boko Haram jihadists have laid waste to northeast Nigeria since they took up arms against the government in 2009. At least 20,000 people have been killed and more than two and a half million more displaced by the unrest.
Rights groups say thousands of women and girls have been abducted by the group. In the most infamous incident, in 2014, more than 200 schoolgirls were taken in the remote town of Chibok.
The jihadists have used abducted females as sex slaves and human bombs, while boys are enlisted to fight. Northeast Nigeria has been buffeted in recent weeks by devastating attacks.
On Friday at least 45 people died and 33 others were wounded in another double suicide attack carried out by female bombers at a marketplace in the town of Madagali.
In October another set of female suicide bombers killed 17 people at a station near a camp for internally displaced persons.
In February 2015, Boko Haram used an eight-year-old to carry out a suicide attack in Potiskum, in Yobe state, and a 10- and 18-year-old pair were involved in a failed July 2014 attack in Funtua, in northwestern Katsina state.