Lagos , Nigeria ( CNN ) -- Nigeria imposed a 24-hour curfew Saturday in the northern city of Kano after assailants killed scores of people and wounded others in a hail of gunfire and coordinated bombings of eight government sites . A military official told CNN that at least 156 people were dead and feared the number would rise . `` The hospitals are not equipped to deal with the influx and severity of the injuries , so we are expecting that figure to go up further , '' the official said . Nwankpa Nwankpa , a Red Cross information officer in the capital , Abuja , said 50 people were injured in the attacks . He said that search and rescue operations are underway and volunteers are working to assist those hurt . The attacks targeted several police stations , barracks and the building housing the assistant inspector general of police in Kano , Nigeria 's second largest city . A passport office , state security headquarters and the immigration office were also hit , police said . Are you there ? Share your story . Terrified residents barricaded themselves in their homes , said Rev . Murtala Mati of the Christian Association of Nigeria . `` The government is really trying but we are afraid ... we are all scared , '' he said . During the attack , assailants entered a police station , freed detainees and bombed it , authorities said . They later canvassed the area in a car led by motorcycles , spraying targets with gunfire . Islamist group Boko Haram claimed responsibility for the blast in a phone call to the Daily Trust , according to journalists at the newspaper . Nigeria closed its borders Saturday with Cameroon and Niger , whom it has accused of allowing the militants to move freely into Nigeria . The government has put in place a state of emergency , and a large deployment of troops has been sent to the north of the country . African Union commission chairman Jean Ping condemned `` in the strongest terms '' the attacks Saturday , and expressed his condolences to the families of those killed and his concern for the many people who were injured . The AU rejects terrorism in all its forms , the statement said , and gives Nigeria its full backing in its efforts to end terror attacks . U.N. Secretary-General Ban Ki-moon is `` appalled at the frequency and intensity of recent attacks in Nigeria , which demonstrate a wanton and unacceptable disregard for human life , '' his office said Saturday in a statement . `` In voicing solidarity with the government and people of Nigeria , the secretary-general also expresses his hope for swift and transparent investigations into these incidents that lead to bringing the perpetrators to justice , '' the statement added . In December , Nigerian President Goodluck Jonathan declared a state of emergency in four northern states . The declaration followed a series of Christmas Day attacks on Christian churches blamed on the Boko Haram group . The man suspected of masterminding those attacks , named Kabiru Sokoto , was briefly captured this week before escaping police custody while being transferred to another prison . Several police officers and the local commissioner are under investigation over his escape . A 50 million naira ( $ 307,000 ) reward was also offered by police Thursday for any information leading to Sokoto 's re-arrest . Northern Nigeria has been wracked by religious violence in recent weeks , including a spate of attacks in early January that killed at least 25 Christians . Boko Haram has been blamed for months of widespread bloodshed , with churches and police stations among the targets . CNN 's David McKenzie contributed to this report .
NEW : The CNN 's Ban Ki-moon is `` appalled at the frequency and intensity '' of recent attacks . A military official tells U.N. that at least 156 people were killed . Nigeria closes its borders with Cameroon and Boko Haram and imposes a state of emergency . The Christian militant group Boko Haram claims responsibility .