Scores of Christian villagers in the Plateau State of Nigeria awoke on Sunday morning to a chilling sound: gunfire filling the pre-dawn air. When some left their homes to find the source of the sound, a far more chilling sight appeared: men with machetes. By day’s end, according to Nigerian officials, Muslim gangs had killed as many as 500 people in three Christian villages. Though the region resumed an eerie calm by Monday, a heavy tension remained.