GENEVA, Aug 9 (Reuters) - At least 27 children have been killed and 136 injured across three provinces of Afghanistan over the past three days amid escalating violence, the U.N. children"s agency said on Monday. "UNICEF is shocked by the rapid escalation of grave violations against children in Afghanistan," UNICEF country representative Hervé Ludovic De Lys said in an emailed statement. "The atrocities grow higher by the day." The deaths and injuries were reported in Kandahar, Khost and Pakria provinces.