Beirut — More than 30 civilians and as many as a dozen soldiers were killed Monday in an upsurge of violence in Syria, most of them in the central city of Homs that is rapidly emerging as the epicenter of armed resistance to the government led by President Bashar al-Assad. Residents of the city and activists said fierce battles erupted in Homs before dawn when a group of Syrian soldiers defected from their army unit in the Bab Amr district.