CAIRO — Clashes and exchanges of artillery fire broke out in Aleppo on Saturday, a monitoring group said, shortly after a Russian-announced cease-fire ended at 7 p.m. local time. A Red Cross official, meanwhile, said that no civilians were evacuated during the three days of the cease-fire, which Moscow had said was intended to allow civilians and injured people to leave rebel-held eastern Aleppo. Evacuations had been impossible because of the poor security situation in the city, said Ingy Sedky, spokeswoman for the International Committee of the Red Cross in Syria. The Red Cross team was unable to enter rebel-held eastern Aleppo, under siege since July, Sedky said.