KADUNA, Nigeria, July 7 (Reuters) - About 125 students were still missing on Wednesday but 28 others had been re-united with their families after an attack by armed men on a boarding school in Nigeria"s Kaduna state, the head of the Kaduna Baptist conference said. Gunmen raided the Bethel Baptist High School overnight on Monday, the 10th mass school kidnapping since December in northwest Nigeria. Parents told Reuters that 180 students typically attend the school, and that pupils were in the process of sitting exams. read more Nigerian authorities have attributed the kidnappings to what they call armed bandits seeking ransom payments. "Search and rescue operations (are) ongoing and we strongly believe that these students will safely return to their parents soon," Reverend I.A.Jangado said in a statement. Humanitarian agencies warn that the rise in school kidnappings is disrupting the education of hundreds of thousands of Nigerian children. read more The United Nations children"s agency UNICEF estimates that more than about 1,120 schools are closed across northwestern Nigeria. Even where schools are open, some parents are too afraid to send their children. Some 300,000-400,000 students in the region are out of school because of insecurity, UNICEF said. "The situation we have found ourself is indeed pathetic, particularly for the parents of the kidnapped students and the school community," said Jangado.