Heavily armed fighters in all-terrain vehicles stormed the town of Kukawa, some 180 kilometres from the Borno state capital, Maiduguri, and opened fire on police and a local market.
Kukawa, near Lake Chad, has been repeatedly targeted by Boko Haram, forcing Nigeria's state-run oil company to abandon prospecting and drilling.
The latest attack happened on Monday and was slow to emerge because telecommunications in Borno have been largely destroyed by five years of violence.
"They burnt the whole market, the police station, government lodge, dozens of vehicles and most houses in the town in indiscriminate rocket and bomb attacks."
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Police officers in Kukawa initially intercepted the insurgents on the outskirts of the town and engaged them in a fight but were forced to retreat because of the gunmen's superior firepower.
Hundreds of residents fled to Maiduguri, joining tens of thousands of others who have abandoned their homes and livelihoods as a result of sustained attacks in Borno and two neighbouring states.
But violence -- and further kidnappings -- have continued unabated.