Gunmen stormed four villages in Nigeria's restive Borno state and killed at least 43 people, officials said on Tuesday.The attacks took place during the weekend in Monguno, an area that has suffered deadly violence in the past, Xinhua quoted police as saying.Borno state police chief Aderemi Opadokun said militant group Boko Haram was suspected to be behind the attack.Local officials put the toll at 43, but said the number could rise as scores of others were injured.Bukar Abdullahi, a local chief, said the gunmen slit people's throats and fired at fleeing crowds. "This happened for several hours," he said.Boko Haram has killed more than 13,000 people since its insurgency started in 2009.