Police stand around the debris of a car at the site of an explosion in Kaduna on April 8, 2012.  A car bomb blast outside a church in northern Nigeria on Easter Sunday killed at least 20 people and put the country on alert over fears of further attacks, rescue officials and residents said. The explosion, a stark reminder of Christmas Day attacks that left dozens of people dead in Africa's most populous nation and largest oil producer, hit the city of Kaduna, a major cultural and economic centre in the north. Motorcycle taxi drivers and passers-by caught much of the blast. AFP PHOTO / STRINGER (Photo credit should read STRINGER/AFP/Getty Images) Photo: Stringer, AFP/Getty Images