YAOUNDE, Cameroon - Suspected Boko Haram Islamist fighters from Nigeria kidnapped around 80 people, many of them children, and killed three others on Sunday in a cross-border attack on villages in northern Cameroon, army and government officials said.The group, which has killed thousands and kidnapped hundreds in its bid to carve out an Islamic state in northern Nigeria, has also targeted Cameroon and Niger over the past year as it seeks to expand its zone of operations.Sunday's kidnappings, among the largest abductions on Cameroonian soil, came as neighboring Chad deployed troops to support Cameroon's forces in the area."According to our initial information, around 30 adults, most of them herders, and 50 young girls and boys aged between 10 and 15 years were abducted," a senior army officer deployed to northern Cameroon told Reuters.He said the early-morning attack had targeted the village of Mabass and other villages along the porous border. Soldiers intervened and exchanged fire with the raiders for around two hours, he added.Government spokesman Issa Tchiroma confirmed the attack, in which he said three people had been killed, as well as the kidnappings. He was not able to say with certainty how many people had been taken in the raid."There was a Boko Haram attack on several localities in the Far North region. The assailants burnt down about 80 homes and kidnapped several inhabitants including women and very young children," he said.In an attack that gained worldwide attention last year, its fighters kidnapped around 200 schoolgirls from the town of Chibok, in northeastern Nigeria.It has stepped up attacks in the region as Africa's biggest economy prepares for a Feb. 14 presidential election.In a video posted online this month, a man claiming to be Boko Haram leader Abubakar Shekau threatened to step up violence in neighbouring Cameroon unless it scraps its constitution and embraces Islam.