GARBA MUHAMMAD Kidnappers killed one person and took an unknown number of students from a university in northwest Nigeria's restive Kaduna state, police said yesterday, in the latest in a series of abductions at educational institutes. Armed groups have repeatedly struck northern Nigerian schools and universities since December, abducting more than 700 students for ransom. The government and security forces have largely been unable to stop the attacks as they struggle to contain worsening violence and criminality across the West African country. The armed kidnappers came on foot and struck Greenfield University in Kaduna at around 8.15 p.m. (1915 GMT)…