JOHANNESBURG — Lacking confidence in government military forces, hundreds of people are fleeing Nigeria's northeast state capital of Maiduguri as Islamic extremists close in, residents said Friday.One prominent resident said soldiers have been evacuating their own families from Maiduguri since Tuesday, the day after the insurgents mounted an attack on Bama, the second largest city in Borno state. Fleeing Bama residents said the attackers warned that their next target is Maiduguri.Bodies littered the streets of Bama, where Air Force jets on Wednesday blew up the armory of the military barracks to prevent the rebels from getting their hands on the weaponry, said Hussain Monguno, a leader of the civic Borno-Yobe People's Forum.Boko Haram has in recent weeks been seizing more towns and controls a large swath of the extreme northeast of Africa's most populous country in a new strategy to form an "Islamic caliphate," mimicking the Islamic State group. At the same time it has begun attacking villages in neighboring Cameroon.Nigeria's military appears incapable of responding to the aggressive land grab by the insurgents who attracted international attention with their April kidnapping of more than 200 schoolgirls who remain captive.Monguno said vigilantes who fled Bama told him that the city of about 200,000 people has been overrun by Boko Haram and that the fighters are killing any men who venture out. The insurgents were largely sparing women and children but killing any men they found and were kidnapping some teenage boys, he said.Monguno said the military insists that its troops are holding Bama, but that Sen. Ahmed Zanna has challenged soldiers to take journalists into the city to prove that claim.A civilian close to the military said the soldiers on Friday were in Konduga, a town 30 kilometers (20 miles) from Bama, but were refusing to advance to engage militants in the city. He spoke on condition of anonymity for fear of retribution from the army.The vigilantes also have reported that the extremists on Tuesday took the towns of Bara and Banki, southwest of Maiduguri in neighboring Yobe state.Boko Haram fighters have attacked the main military barracks and an air force base in Maiduguri in the past, and sent suicide bombers who killed scores of people.More than 100 Nigerian soldiers abandoned the battle for Bama and fled across the border into Cameroon, a Western worker there told The Associated Press on Thursday, requesting anonymity because of the sensitivity of the subject. Last week, nearly 500 soldiers fled another border town fight and crossed into Cameroon, according to Cameroonian officials who helped repatriate the troops.The U.S. assistant secretary for African affairs, Linda Thomas-Greenfield, said Thursday the United States is preparing to launch a major border security program for Nigeria and its neighbors."We are very troubled by the apparent capture of Bama and the prospects for an attack on and in Maiduguri," she said Thursday at a high-level meeting with Nigerian officials in Abuja, the capital.Some 26,500 residents have fled Bama to Maiduguri this week, the Nigerian Emergency Management Agency said, joining nearly 12,000 who fled Gwoza when it was taken by Boko Haram two weeks ago. The U.N. refugee agency says nearly 650,000 Nigerians have been forced from their homes by the insurgency and are displaced inside the country, with tens of thousands more sheltering in neighboring countries. Many refugees are not counted because they have been taken in by family and friends, and human rights and aid workers estimate more than 1.5 million are affected.Residents leaving Maiduguri Friday described a confused situation with refugees from the fighting still coming into the city even as they and others were fleeing. Three residents spoke on condition of anonymity for fear their flight would anger officials.The Lagos-based chairman of the Nigerian Human Rights Commission, Chidi Odinkalu, posted a tweet saying: "After 41 yrs in #Maiduguri, my brother will quit this weekend to escape insurgency; says motor (bus) parks are filled with fleeing residents."Boko Haram has taken towns to the north, east and southeast of Maiduguri in recent weeks.Nigerian soldiers have told The Associated Press that they are outnumbered and outgunned by Boko Haram. They charge that they are deposited in the bush with orders to fight but without enough ammunition, food or even water despite blistering heat. And they said they are demoralized by the apparent collaboration of senior and junior soldiers with the extremists.President Goodluck Jonathan has suggested there may be Boko Haram backers and supporters even in his Cabinet. At the beginning of this year he fired all his military service chiefs and the defense minister.Jonathan's party and the biggest opposition coalition have traded accusations about who is sponsoring and arming Boko Haram, but none have provided any proof.