A child bomber killed six people and wounded dozens on Tuesday outside a bus station in the heartland of the Boko Haram Islamist insurgency in northeastern Nigeria.
Witnesses reported seeing a "young girl" approaching the station in the Yobe state capital Damaturu around 7:00am (0600 GMT) and refusing to be searched by security guards at the gate before blowing herself up.
"A private taxi... drove out of the park. As soon as the car came close, she detonated the explosives. Six people in the car were killed. She was also killed," bystander Sani Dankamasho told AFP.
State police told AFP the bomber was aged around 14 but Dankamasho and other witnesses said she looked closer to 12.
The attack came just hours after United Nations chief Ban Ki-moon wrapped up two-day a visit to Africa's largest economy during which he hailed its "greater stability and peace" under its new leader as he commemorated a deadly 2011 attack on the global body by Boko Haram militants.
Police and witnesses reported a second attack 10 minutes after the bus park bombing, in which a suicide bomber managed only to kill himself and slightly wound a bystander on the outskirts of Damaturu.
"There were two suicide blasts in Damaturu today. The first one happened outside the motor park and the second one occurred in Pompomari on the outskirts of Damaturu. But only the bomber has died in the second blast," said Toyin Gbadegesin, a spokesman for Yobe state police.
"In the first blast outside the motor park, six people were killed and 42 others were injured by a female suicide bomber. The injured are receiving treatment in hospital," he said.
No group immediately claimed responsibility for the bus park bombing but it bore the hallmarks of Boko Haram, which has in recent weeks used young women to carry out bloody suicide attacks in the restive northeast.
"The dead have been evacuated to a mortuary while the injured victims are currently being attended to by health and emergency workers," local government spokesman Abdulahhi Bego said in a statement.
Boko Haram has stepped up attacks in Yobe and two other states in its northeastern bastion since President Muhammadu Buhari came to power on May 29 raising hopes he could tackle the worsening security situation.
The Islamists have also carried out deadly ambushes across Nigeria's borders and in recent weeks suicide bombers, many of them women, have staged several attacks in Nigeria, Cameroon and Chad.
The fresh wave of violence has claimed more than 1,000 lives over the last three months, dealing a setback to a four-country offensive launched in February that had chalked up a number of victories against the jihadists.
An 8,700-strong Multi-National Joint Task Force, drawing in Nigeria, Niger, Chad, Cameroon and Benin, is expected to go into action soon.
Military spokesman Colonel Rabe Abubakar said the chief of defence staff, General Gabriel Olonisakin, had met regional military chiefs in Chad's capital N'Djamena. He gave no date for the meeting but said the generals "finalised details of deployment".
Buhari has vowed to destroy Boko Haram, and replaced his military leaders earlier in August, ordering his new chiefs-of-staff to end the jihadist bloodshed within three months.
The military under his predecessor Goodluck Jonathan was heavily criticised for its poor handling of the insurgency and its failure to free more than 200 schoolgirls abducted from the northeastern town of Chibok in April last year.
The "Bring Back Our Girls" campaign will on Thursday mark 500 days since the girls were captured and is due to meet the country's new chief of defence staff Abayomi Gabriel Olonisakin later on Tuesday.
"I want to reiterate my support for the Chibok girls, and so many other innocent abducted girls and boys, whose names and fate remain unknown," Ban said before leaving for France late on Monday.
"It is intolerable that their lives and schooling has been disrupted in this way. The whole world has been moved by their fate."