Boko Haram has launched a major offensive in Nigeria's northeastern city of Maiduguri and the town of Monguno, and in fierce fighting Sunday that killed more than 200 combatants, Nigerian troops clashed with with the fighters who attacked Maiduguri from three fronts.
At the same time, Boko Haram fighters continued scorched-earth attacks on villages some 125 miles to the south in Adamawa state, slitting throats of residents, looting and burning homes and abducting dozens of trapped women and children, according to Vandu Kainu and other escaping survivors.
Adamawa state legislator Adamu Kamale appealed for troops to protect civilians in Michika, where six villages are under attack. "The attacks have continued since Friday with no presence of security operatives," he said.
The army was claiming some success in its attempts on Sunday to stop the fall of Maidiguri, the largest city in Borno State, but local sources said that fighting continued in some areas.
Local residents told the AFP news agency that Boko Haram fighters first attacked the Jintilo settlement, about three miles from Maiduguri.
"Troops are repelling a simultaneous attack on Monguno and Maiduguri by terrorists," Nigeria's defense headquarters said on Twitter. It said a land and air operation against the group was ongoing.
The fighting erupted as U.S. Secretary of StateJohn Kerry arrived in the country on Sunday and met with President Goodluck Jonathan and his chief rival candidate, former general Muhammadu Buhari, ahead of next month's presidential election.
"This will be the largest democratic election on the continent," Kerry said. "Given the stakes, it's absolutely critical that these elections be conducted peacefully — that they are credible, transparent and accountable," Kerry said in Lagos, Nigeria's commercial capital nearly 1,000 miles southwest of Maiduguri.
Kerry told reporters afterward that he won pledges from both to refrain from violence.
He also issued a warning: Anyone responsible for inciting post-election mayhem will be barred entry to the United States, where millions of Nigerians live.
Kerry promised more U.S. support in the fight against Boko Haram if the elections take place peacefully and democratically.
In Maiduguri, the biggest city in northeastern Nigeria, troops blocked roads into the city, which also prevented civilians from escaping.
Defense Ministry spokesman Brig. Gen. Chris Olukolade said Sunday evening that troops successfully repelled attacks on Maiduguri and Konduga, 25 miles to the southeast.
But he said they were mounting air raids in Monduno, a town 88 miles northeast of Maiduguri, which Boko Haram seized Sunday morning.
Fears have been growing for months about a possible strike on Maiduguri after the group began seizing towns and villages in three northeastern states about six months ago.
On Jan.3, Boko Haram captured the fishing hub of Baga, in the far north of Borno State, which security analysts said put the fighters in a better position to strike south Maiduguri, the state capital.
Maiduguri would be a major prize for the group, which is trying to carve out an Islamic state in the region.
The group control large parts of Borno State and some areas of neighboring Adamawa and Yobe states.
Al Jazeera and news services