Two girls have blown themselves up near a crowded mosque in north-east Nigeria's biggest city, killing about 30 people, witnesses said.
It is the fourth suicide bombing this month in Maiduguri, the birthplace of the Boko Haram Islamic extremist group.
Fishmonger Idi Idrisa said one teenager exploded as she approached the mosque crowded with people from the nearby Baga Road fish market, performing afternoon prayers during the holy month of Ramadan.
The second teenager appeared to run away and blew up further away, killing only herself, he said.
Boko Haram has kidnapped hundreds of girls and women, and the number of female suicide bombers has raised fears that it is using the captives in its campaign.
A military bomb disposal expert has said most bombs carried by girls and women have remote devices, meaning the carrier cannot control the explosion.
Boko Haram has stepped up attacks since Nigeria's new president Muhammadu Buhari announced the military command centre was moving from Abuja, the capital in central Nigeria, to Maiduguri, the capital of Borno state.
The attacks come as Nigeria and its neighbours prepare to strengthen a multinational army that this year drove Boko Haram out of the towns and villages where it had set up a so-called Islamic caliphate.
But bombings and hit-and-run attacks have continued along with cross-border raids.
On Thursday, a group of extremists attacked two towns in neighbouring Niger, setting homes ablaze and killing at least 40 people, the government said.
In its first attack on Chad, suicide bombers a week ago simultaneously attacked two buildings including the national police academy in the capital N'Djamena, killing at least 33 people and wounding more than 100.