(YOLA, Nigeria) — Soldiers abandoned checkpoints and fled into the bush, leaving five villages and a town at the mercy of Islamic extremists who killed at least 13 people and firebombed a theological college in overnight attacks in northeast Nigeria that lasted hours, survivors said Thursday. On Tuesday, extremists killed 59 students when they struck a school in Yobe state, hours after soldiers were inexplicably withdrawn from a roadblock set up to protect the institution. The recent string of assaults in an Islamic uprising gripping the northeast of Africa's biggest oil producer comes amid widespread criticism of military failures despite a 9-month-old state of emergency. "It is curious that under an emergency rule when security operatives are on red alert, this mayhem still persists," Senate president David Mark said Wednesday in a statement calling the attacks an "open declaration of war." Visiting African leaders also condemned the attacks and expressed solidarity with Nigeria as it began official centenary celebrations Thursday marking the unification under British colonizers of the mainly Muslim north and majority Christian south. It began with a conference on human security and a keynote address by French President Francois Hollande, who said Nigeria's struggles are France's struggles. He pledged support for Nigeria's fight against terrorism. The latest attacks began around 8:30 p.m. Wednesday on Kirchinga village of Adamawa state, near the border with Cameroon, with insurgents in a convoy of 13 all-terrain pickup trucks shooting as they lobbed firebombs into thatch-roofed huts. Villagers fled but the attackers pursued them all the way to neighboring Shuwa town, according to survivors who spoke on condition of anonymity for fear of reprisals. "When the soldiers at the military checkpoints saw the number of the attackers, they retreated into the nearby bushes as the gunmen operated without challenge during the operation that lasted throughout the night," said a pastor in Shuwa. Blasts from firebombs could still be heard at 2:30 a.m. Thursday, survivors said. The pastor said the soldiers remained in hiding while the assailants set numerous buildings on fire in Shuwa,(http://stats.wordpress.com/b.gif?host=world.time.com&blog=19871253&post=136910&subd=timeglobalspin&ref=&feed=1)