Suspected Boko Haram militants escalated their attacks killing at least 11 people including three aid workers in an attack on a military facility in Borno State late on Thursday, according to two security reports.
The raid in the town of Rann marked the latest high-profile attack by militants in the northeast, coming less than two weeks after militants abducted 110 girls from a school in Dapchi in neighbouring Yobe state.
The United Nations confirmed three aid workers, all Nigerian nationals, were killed in the attack in Rann, near the Cameroon border, and said a female nurse was missing, feared abducted. It said it was also concerned other civilians may have been killed or injured.
Four soldiers and four police officers were also killed, according to the Nigerian security reports seen by Reuters.
The militants, armed with rocket-propelled grenades and truck-mounted guns, initially overpowered soldiers in a firefight at the military facility but the armed forces later regained control, according to the security reports.
The attack happened “after dark” outside a camp housing some 55,000 people displaced by the conflict and appeared to target the military, said UN spokeswoman Samantha Newport.
A civilian militia source in Rann, Borno State which is some 175 kilometres (110 miles) from Maiduguri, the Borno state capital, and a senior military source gave an identical death toll.
They also said eight soldiers were killed in the attack but there was no immediate official confirmation.
Newport said: “Three aid workers were killed, one aid worker was injured and one aid worker is missing, feared abducted.
“Of the aid workers that were killed, two worked for the IOM (International Organization for Migration) in camp management; and one was a medical doctor working as a third party consultant for UNICEF,” the UN children’s agency, she said.
Newport said the injured and missing were both women. All those involved were Nigerian, she added.
The IOM also said Friday that “a large number” of Boko Haram members attacked the base in Rann, a day earlier with automatic weapons, rocket-propelled grenades and gun trucks.
At a U.N. briefing in Geneva, IOM spokesman, Joel Millman said the two staffers, Ibrahim Lawan and Yawe Emmanuel, were among humanitarian workers killed. Four soldiers and four mobile police also died, and another three humanitarian workers were injured.
IOM Director of Operations and Emergencies Mohammed Abdiker said in a statement that the agency was “outraged and saddened” by the attack.
Boko Haram fighters killed nine people from the Rann internally displaced persons (IDP) camp in September last year, as they worked on farms just outside the town.
In January last year, a botched Nigerian air strike intended to hit jihadist fighters killed at least 112 people as aid workers distributed food.
Commanders at the time called the bombing a mistake and blamed “the fog of war”.
An air force board of inquiry later blamed “lack of appropriate marking of the area” for the bombardment and an unexpected gathering of people at the location.
Friday’s attack was a further setback for President Muhammadu Buhari, who took office in May 2015 vowing to improve security and who has repeatedly said the Boko Haram insurgency has been defeated.
The government said on Friday that it was extending to neighbouring countries the search for the girls taken in Dapchi, which is some 400 km (250 miles) west of Rann.
Borno state, where Rann is situated, is the epicentre of the Boko Haram insurgency, which aims to impose a strict interpretation of Islam in northeast Nigeria. More than 20,000 people have been killed and some two million forced to leave their homes since 2009.
Two of the aid workers who died were contractors with the International Organization for Migration, working as coordinators at a camp for 55,000 displaced people in Rann, the United Nations said. The third was a doctor employed as a consultant for UNICEF.
“We call on authorities to ensure the perpetrators are brought to justice and account,” Edward Kallon, the U.N. Humanitarian Coordinator in Nigeria, said in a statement.
Attacks on aid workers are rare, but not unheard of. In December, four people were killed when a World Food Programme (WFP) convoy was ambushed in Borno state.
Boko Haram held a swathe of territory in northeast Nigeria around the size of Belgium in late 2014. It was pushed out of most of that land by Nigeria’s army, backed by troops from neighbouring countries, in early 2015.
Although it has failed to control large areas of land since then, the group continues to carry out suicide bombings and gun raids in northeast Nigeria, Cameroon, Niger and Chad.
The camp for displaced people in Rann was bombed in an accidental Nigerian Air Force strike last year, killing up to 170 people.