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.
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NEW: The U.N.'s Ban Ki-moon is "appalled at the frequency and intensity" of recent attacks
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A military official tells CNN that at least 156 people were killed
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Nigeria closes its borders with Niger and Cameroon and imposes a state of emergency
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The Islamist militant group Boko Haram claims responsibility
Nigeria closed its borders Saturday with Cameroon and Niger, whom it has accused of allowing the militants to move freely into @placeholder.