Another 11 people were wounded in the violence on Wednesday, which came ahead of a visit by UN Secretary General Antonio Guterres to the country next week.
The clashes occurred in the town of Pombolo, in a region where tensions have flared between Muslim and Christian militias since May in which dozens of civilians have been killed.
Seraphin Embondza, commander of the UN's MINUSCA mission in the country, told the UN radio station Guira FM that the wounded had not yet been evacuated from the town, where no UN troops had been stationed.
One of the world's poorest nations, the Central African Republic has been struggling to recover from a three-year civil war between the Muslim and Christian militias that started after the 2013 overthrow of leader Francois Bozize.
Also Read
The United Nations maintains some 12,500 troops and police on the ground to help protect civilians and support the government of Faustin-Archange Touadera, who was elected last year.
UN chief Guterres is expected to arrive on Tuesday in a visit aimed at drawing attention to a "forgotten crisis" and its heavy toll on aid workers and UN peacekeepers.
Some UN officials have raised alarm over indications of genocide in the country. Guterres said there was "ethnic cleansing" in many parts of the country.
Disclaimer: No Business Standard Journalist was involved in creation of this content