A female aid worker was also missing while one other sustained injuries in the attack.
Samantha Newport, Head of Communications, UNICEF Office for Coordination of Humanitarian Affairs (OCHA), confirmed the incident to News Agency of Nigeria on Friday in Maidguri.
Newport said two of the deceased were personnel of UN client organisation, International Organisation of Migration ( IOM), deployed in Rann as camp managers.
She added that others killed were a medical doctor working as consultant with UNICEF and an aid worker with International Committee of Red Cross (ICRC) affiliate organisation.
The UNICEF communications head said a female nurse was abducted, while another female aid worker was injured in the attack.
She explained that all the deceased personnel were Nigerians, adding that the world body
would soon issue a statement on the incident.
Meanwhile, competent sources in Rann told NAN that the insurgents attacked the town at about 7pm on Thursday.
The source added that the insurgents, moving on gun trucks and motorcycles, infiltrated the town and attacked a military base and a displaced persons’ camp.
Military authorities have yet to comment on the incident.