Dozens of passengers kidnapped during a train attack in northern Nigeria in late March are being used as human shields by their captors, President Muhammadu Buhari has said. Buhari said this had further complicated rescue efforts. At least eight people were killed, and more than two dozen injured when gunmen opened fire on a packed commuter train traveling from the capital Abuja to the northern city of Kaduna on March 28. A survivor of the attack told CNN at the time that the train was hit by two explosions before the gunmen opened fire on trapped passengers. After bombing the tracks, the gunmen surrounded the carriages and opened fire, said eyewitness Musa Bashir Usman. Around 168 passengers of the ambushed train could not be accounted for last month by the Nigerian Railway Corporation. Local media reported last week that a pregnant woman said to be among those kidnapped had given birth while in captivity.