The worst violence to hit Central African Republic’s capital, Bangui, in a year further deteriorated Monday as more than 500 inmates escaped from a prison, officials said. Forty-two people had been killed in several days of clashes, including a teenage boy who was decapitated. The unrest erupted as the transitional president, Catherine Samba-Panza, was attending the United Nations General Assembly in New York. Clashes were set off by the death of a Muslim man whose body was left near a mosque. Muslim militants then attacked a Christian neighborhood, with weekend clashes leaving several dozen people dead.

Among the hundreds who escaped Nagaragba Central Prison on Monday were at least 60 high-level convicts, including fighters from both Muslim and Christian militant groups, the authorities said. The escape was confirmed by witnesses and Thierry Ngoalessio, the head clerk at Bangui’s court. The United States swiftly condemned the unrest, and pledged its support for Ms. Samba-Panza’s government. Amid the near-anarchic conditions in Bangui, elections set for Oct. 18 seemed increasingly unlikely.