BBC News Published image captionThe remains of desks are all that is left from the straw-hut classrooms At least 20 children have died after they became trapped in a fire at a school in Niger's capital, Niamey. It started late on Tuesday afternoon when the children were in lessons, many in straw-hut classrooms. The flames blocked the school gate, so most pupils had to escape over a wall, said a teacher's union official quoted by Reuters. Most of those who did not manage to escape were attending the school's nursery, officials say. The government-run junior and pre-school in the Pays Bas district of the city had a mixture of brick and straw-hut classrooms, BBC Hausa's Tchima Illa Issoufou reports from Niamey.