Twelve people were killed and more than 40 more were wounded in shootings in Chicago during the Memorial Day long weekend.

The Cook County Medical Examiner's office on Tuesday confirmed the 12 deaths. Police say the spate of gunfire injured dozens more, including a 4-year-old girl who was shot in the head at about 8 p.m. Friday on the city's South Side.

Chicago has seen similar spikes of violence on previous Memorial Day weekends. It is also the start of a season when the numbers of homicides typically climb. Police have in recent years responded by flooding the streets with officers working overtime to combat the violence.

Department statistics show that as of mid-May there were 133 homicides in Chicago — 19 more than in the same period last year.