MEXICO CITY Armed assailants on Tuesday gunned down two close aides to Mexico City Mayor Clara Brugada in what authorities call an unprecedented attack on the capital’s government. Ximena Guzman, her personal secretary, and Jose Munoz, a political advisor, were targeted and followed by armed men on a motorcycle through one of the city’s main avenues, in what appears to have been a direct coordinated assault, said police. Both were gunned down at close range. The city's Citizen Security Ministry