Scores of Boko Haram gunmen riding in armoured vehicles razed a remote northeast Nigeria town on Monday and opened fire on residents who tried to flee into neighbouring Cameroon, witnesses said. "They have burnt the market, customs office, police station and almost every shop in the town and killed many people but I can't say how many," said Musa Abba, a resident of Gamboru Ngala in an account supported by several others. "They have taken over the whole town."