A Nigerian Air Force fighter jet fired on a refugee camp in northeast Nigeria on Tuesday, killing refugees and aid workers while wounding scores of other civilians, accordng to the military and aid organizations.

The death toll has risen to 76, according to the International Red Cross and Red Crescent Movement (ICRC). The latest figure is a significant increase from an earlier report by the medical charity Doctors Without Borders (MSF).

They put the death toll at 52, with at least 120 wounded. MSF called the bombing "shocking and unacceptable." The military has acknowledged responsibility for the bombing but has yet to provide specific numbers on the death toll.

MSF also tweeted pictures from the scene showing rubble and many wounded people seeking shelter in nearby tents.

The International Committee of the Red Cross (ICRC) said six of its aid workers had been killed while another 13 had been injured.

The incident happened around 9 am (0800 UTC) around Rann, in the far northeast of Borno state near the border with Chad and Cameroon. Borno state is the epicenter of the Boko Haram insurgency, which has left some 15,000 people dead and displaced nearly two million civilians since 2010.

Nigeria's President Muhammadu Buhari said in a statement that he "received with regret" news of the bombing, adding that he sympathized with the families of the dead and injured. Buhari also pledged the support of the federal government "in dealing with the situation and attending to the victims."

Fog of war

Major General Lucky Irabor, who heads the military operation against the militants, said the military would conduct a full investigation and that the Air Force would not deliberately target civilians.

Irabor said he ordered the mission based on geographic coordinates of "Boko Haram terrorists" in the area near where the refugee camp was located.

"[This is] the result of fog of war," Irabor said. "It is unfortunate. That is the reason why this war must come to an end."

Locals villagers in the past have reported some civilian casualties in near-daily bombardments against Boko Haram in the area.

The bombing comes as Nigeria's military makes territorial gains against the extremist group, pushing them out of their remote bases in Borno state.

Boko Haram has stepped up attacks over the last few weeks as the end of the rainy season has enabled fighters to move more easily in the bush. Northeastern Nigeria has been the focus of the jihadist group's seven-year insurgency to create an Islamic caliphate.

cw/rs/se (AP, AFP, dpa, Reuters)