(Reuters) - An 11-year-girl was shot and killed during a slumber party as violence struck Chicago during the weekend, local media outlets reported on Sunday.

At least 40 people were shot, and four killed, in weekend violence in the third-largest U.S. city, WMAQ-TV, Chicago, reported.

The deaths included an 11-year-old girl, shot in the head inside a first-floor bedroom Friday night after someone fired a gun from outside the house, said Chicago Police Officer Jose Estrada.

Shamiya Adams, who died the next day, had been sitting on the floor during a sleep-over at her best friend's home, the Chicago Tribune reported.

The Chicago Police Department Sunday had not released an official tally of the weekend violence. But reports of another outbreak of gunfire came as the city has been grappling with a wave of summer violence.

City officials condemned as unacceptable a spree of gunfire during the Fourth of July holiday weekend that left 17 dead, with 53 people shot, including five by police. Authorities said at the time that shooting deaths in Chicago were down for the year.

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