Hundreds of Boko Haram
gunmen launched a predawn attack Sunday on Maiduguri, the capital of Borno state.
Soldiers repelled the attacks, and officials have since eased a curfew imposed as a result, said Col. Sani Usman, a military spokesman.
But a simultaneous attack on nearby Monguno town was a different story.
The Islamist militants captured the town, together with its military barracks, a Nigerian military officer said.
It's unclear how many people were wounded or killed during the battle for the two cities.
"Our soldiers initially repelled the terrorists but they mobilized more fighters and came back in full force. They overwhelmed our troops and forced them to retreat," the military officer said. He asked not to be named because he's not authorized to speak to the media.
Monguno is about 135 kilometers (85 miles) from Maiduguri. The former has a population of 100,000 while Maiduguri has about 600,000.
Both cities are near the Chad and Cameroon borders, which would give the militants an entry point into those countries.
Monguno and its military post served as a buffer to keep the militants away from Maiduguri. Its fall leaves Maiduguri vulnerable and puts the extremists in a better position to seize the city.
Cornered since January 3
Boko Haram had been confined to the fishing town of Baga since its fighters seized it on January 3. Thousands were feared killed in that attack,
which lasted days.
Borno Gov. Kashim Shettima said soldiers will continue their crackdown on the militants.
"So long as we have the resources, we will continue to regard the efforts to reclaim peace our No. 1 area of commitments," he said.
" I want to reassure the good people of Borno State that we will never abdicate from our responsibility as those they entrusted with leadership."
Elections next month
The attack came a day after President Goodluck Jonathan made a campaign stop in Maiduguri ahead of the February 14 presidential election. U.S. Secretary of State John Kerry was also in the nation Sunday to call for peaceful elections.
Boko Haram has terrorized northern Nigeria regularly since 2009, attacking police, schools, churches and civilians, and bombing government buildings. The Islamist group has said its aim is to impose a stricter form of Sharia law across Nigeria, which is split between a majority Muslim north and a mostly Christian south.