The schoolgirls were taken from their hostels by gunmen who raided the Government Girls’ Secondary School in the town of Jangebe, a high-ranking government official with knowledge of the incident told CNN.A police officer was killed in the attack, according to the source, who did not want to be named as he did not have permission to speak on record.”They came on about 20 motorcycles and they marched the abducted girls into the forest,” the source said. “The bandits arrived around 1.45 a.m. and they operated ’til about 3 a.m. “The sad part is that there’s a military checkpoint that is about four minutes away from the school,” he added. Read MoreAbout 500 students are normally at the boarding school, of whom around 315 were taken by the gunmen. Others managed to flee and return to their hostels, the source said. Why can't Nigeria protect its children from Boko Haram?A spokesman for the police in the state told CNN that a detailed statement would be released as they piece together what happened. He declined to comment on the number of students kidnapped in the incident. The latest abduction comes barely two weeks after at least 42 people, including students, were kidnapped in a similar raid on a state school in Niger state, in Nigeria’s Middle Belt region. A student was killed in that attack, while 27 students, three teachers and nine family members, were abducted. Their current whereabouts are unknown.UNICEF Friday expressed concern at reports of the overnight attack. “We are angered and saddened and by yet another brutal attack on schoolchildren in Nigeria,” said Peter Hawkins, UNICEF representative in Nigeria.”This is a gross violation of children’s rights and a horrific experience for children to go through — one which could have long-lasting effects on their mental health and well-being. We utterly condemn the attack and call on those responsible to release the girls immediately and for the government to take steps to ensure their safe release and the safety of all other schoolchildren in Nigeria.”Children should feel safe at home and at school at all times — and parents should not need to worry for the safety of their children when they send them off to school in the morning,” said Hawkins.Many parents are worried about the safety of their children in schools in the north of Nigeria. In December, at least 300 schoolboys were kidnapped by bandits in Katsina, President Muhammadu Buhari’s home state. The students have since been released.The most prominent of the school kidnapping cases in the country was that of the Chibok schoolgirls who were abducted by Boko Haram in April 2014.