One hundred and ten girls are missing after an attack on a school in northeast Nigeria by suspected Boko Haram insurgents, the information ministry said on Sunday, in what may be one of the largest abductions since the Chibok kidnappings of 2014.

The Islamist militant group attained international notoriety after abducting more than 270 schoolgirls from the town of Chibok. That case drew global attention to the insurgency and spawned high profile social media campaign Bring Back Our Girls.

Boko Haram, whose name translates as “Western education is forbidden” in the Hausa language widely spoken in northern Nigeria, has killed more than 20,000 people and forced two million to flee their homes in a violent insurgency that began in 2009.

President Muhammadu Buhari, the 75-year-old former military ruler elected in 2015 after vowing to crush Boko Haram, has described the disappearance of the girls after Monday’s attack in the town of Dapchi, Yobe state, as a “national disaster”.

The insurgents drove into the town of Dapchi on Monday and attacked the girls’ school, sending hundreds of students fleeing. Some of the attackers were camouflaged, with witnesses stating that a number of students thought they were soldiers.

“The federal government has confirmed that 110 students of the Government Science and Technical College in Dapchi, Yobe State, are so far unaccounted for, after insurgents believed to be from a faction of Boko Haram invaded their school on Monday,” the information ministry said in a statement.

There had been confusion over the number of those missing, with estimates ranging from about 50 to more than 100. State police, Yobe government and others had given different figures while a parent representing families of girls who disappeared on Friday told Reuters 105 were missing.

Yobe state government added to the confusion when it said on Wednesday that dozens of the girls had been rescued, only to issue a statement the next day saying the schoolgirls were mostly still unaccounted for, sparking anger among locals.

The Nigerian Air Force on Sunday said the chief of air staff had “directed the immediate deployment of additional air assets and Nigerian Air Force personnel to the northeast with the sole mission of conducting day and night searches for the missing girls”.

“The renewed efforts at locating the girls are being conducted in close liaison with other surface security forces.”

Information Minister Lai Mohammed, who was part of a delegation of ministers who met parents and teachers in Dapchi and announced the number of missing girls, also said police and security officials had been deployed to schools in the state.