CHICAGO (AP) — A woman working at a Chicago thrift store was killed when a gun that was in dropped-off clothing accidentally discharged, hitting her in the chest.

Chicago police say 54-year-old Carmen Dominguez and a male co-worker were sorting the donated clothing in a back room of the store in the city's Washington Heights neighborhood early Friday when the co-worker shook a sock. A .22-caliber gun inside the sock fell into the co-worker's hand and discharged.

The wounded woman was taken to a hospital where she was pronounced dead.

Relatives said she was a wife and mother of two children.

The U.S. Occupational Safety and Health Administration is investigating.