Boko Haram jihadists killed four people during a raid on a camp for civilians displaced by the Islamist group's violent insurgency in Nigeria's troubled northeast, security sources said on Saturday.The gunmen entered the camp in the town of Banki near the border with Cameroon on bicycles and on foot Friday night and opened fire."Boko Haram terrorists entered Banki IDP (internally displaced people) camp last night and killed four people, injured four others and took supplies away with them," a military officer in the town told AFP. The shots drew the attention of soldiers and policemen outside the camp, who then engaged the militants in an hour-long gun battle, said the officer, who asked not to be named."Two terrorists were killed in the fight and the rest fled," he added.A member of a militia force assisting the military said the jihadists used ladders to scale a ditch dug around the camp to stop such an incursion."This was why security personnel keeping sentry at the entrance of the camp were taken off-guard," he said."From all indications, they came to steal food supplies."Hours later two soldiers were wounded when their patrol vehicle hit a landmine planted by the fleeing jihadists at Freetown village, nine kilometres away, he added.Banki, which is 130km southeast of Borno state capital Maiduguri, houses 45 000 displaced people in a sprawling camp.The camp was relatively calm after opening in March 2015.However Boko Haram has since raided it numerous times, including in February when militants stole food and clothing before being repelled by soldiers.Eleven people were killed in another raid in September.Boko Haram's nine-year armed violence to establish a hardline Islamic state in remote northeastern Nigeria has killed more than 20 000 people.* Sign up to News24's top Africa news in your inbox: SUBSCRIBE TO THE HELLO AFRICA NEWSLETTERFOLLOW News24 Africa on Twitter and Facebook.