Eleven people were killed and at least four others were injured when an unidentified armed group opened fire in a restaurant in the city of Chihuahua, capital of the northern Mexican state of the same name, the authorities said Friday according to DPA. The attackers, traveling in at least three vehicles, arrived at the Rio Rosas bar close to midnight and said they were federal agents. They then started shooting, police said based on the statements of survivors. One journalist who wrote editorials for the Chihuahua daily El Diario was among those killed. Close to 3,500 people have been killed so far this year in Mexico in actions related to organized crime, according to media reports.