Gunmen who attacked a boarding school for the children of Christian missionaries and diplomats in Pakistan left a note saying the assault was in retaliation for injustices they said were experienced by Muslims in various conflict zones. Six adults, all Pakistani nationals, were killed in Monday's shooting at the Murree Christian School 50 kilometers north of Islamabad, and at least four others were hurt. The dead included two hired security guards, a cook, a receptionist, a carpenter and a man described as a bystander. Thirty Americans were among the 150 pupils between the ages of six and 18 who were...