In late July 2012, the conflict reached Aleppo in earnest when fighters from the surrounding countryside mounted their first offensive there, apparently trying to capitalise on momentum gained during the Damascus assault. Then, some of the civil war's "most devastating bombing and fiercest fighting" took place in Aleppo, often in residential areas. In the summer, autumn and winter of 2012 house-to-house fighting between armed opposition and government forces continued, and by the spring 2013 the Syrian army had entrenched itself in the western part of Aleppo (government forces were operating from a military base in the southern part of the city) and the armed opposition in the eastern part with a no man's land between them. One estimate of casualties by an international humanitarian organization is that by this time 13,500 had been killed in the fighting– 1,500 under 5 years of age – and that another 23,000 had been injured. Local police stations in the city, used as bases of government forces and hated and feared by residents, were a focus of much of the conflict.