At least 50 people were killed in multiple attacks by armed 'bandits' on villages in an area of northern Nigeria rife with cattle theft and kidnappings, local officials said on Monday. Sources said around 100 armed assailants stormed into the villages of Kerawa, Zareyawa and Minda in Kaduna state at dawn on Sunday, gunning down worshippers as they left a mosque for morning prayers before killing residents, burning and looting homes."So far 50 bodies have been recovered but the figure is not conclusive and is very likely to rise as rescue efforts are still under way," Zayyad Ibrahim, a lawmaker in the Nigerian parliament, told AFP on Monday.Several people were injured in the attacks and were taken to nearby hospitals Ibrahim said.The attacks were in retaliation for villagers allegedly assisting recent army operations against the so-called bandits in their forest hideouts, local counsellor Dayyabu Kerawa told AFP.READ | Cameroon army blames 'unfortunate accident' for village massacre"The bandits accused residents from the targeted villages of providing information about their hideouts to the military," said Kerawa."We buried 51 victims yesterday (Sunday) afternoon," Kerawa said.Kaduna police spokesman Mohammed Jalige said authorities were investigating the attacks. Violence has soared in northwest Nigeria in recent years as criminal gangs involved in cattle rustling and kidnapping have carried out bloody raids on villages.READ | Bandits kill 30 in Nigeria attack - policeThe groups attack from hideouts in nearby forests exploiting a lack of security across the region.The Birnin Gwari and Giwa districts of Kaduna state have been hit by violence and repeated reprisal attacks between bandits and local vigilante groups.Security forces in February announced a sweeping operation aimed at armed gangs in the area. Last month 21 people, including 16 members of one family, were killed when bandits attacked a village in a reprisal attack.Authorities in several states in northwest Nigeria have sought peace deals with the bandits to stop the bloodshed but these have failed to end the instability.