A Nigerian air force jet has accidentally killed and Injured many civilians in Rann, in the north-east of the country, the military has said.
Aid workers are among the casualties - the Red Cross says six of its workers are confirmed dead.
The attack took place near Nigeria's border with Cameroon where the army has been fighting Boko Haram militants.
Army spokesman Maj-Gen Lucky Irabor said the jet's pilot had mistakenly believed he was attacking insurgents. He said the mission had been ordered, based on intelligence about a gathering of Boko Haram fighters.
Nigerian President Muhammadu Buhari has sent a message expressing his dismay at the loss of life and pleading for calm.
His spokesman said Mr Buhari's administration would offer help to the government of Borno state "in attending to this regrettable operational mistake".