Authorities in northern Nigeria’s largest city have begun evacuating more than 5,000 street children seen as a “security threat” and a growing concern as an economic crisis forces more to fend for themselves. The Hisbah, a regional police force tasked with enforcing Islamic Sharia law, have carried out midnight raids on motor parks, markets and street corners in the regional capital, Kano, since the beginning of the year, evacuating children as they sleep.