ARLINGTON HEIGHTS - Friends and family are mourning the death of an Arlington Heights woman who drowned while rescuing a 9-year-old boy in a Wisconsin lake.

According to the Vilas County Sheriff's Department, Karen Wessel, 47, died Tuesday when she went under the water in Star Lake in Wisconsin after helping a boy who was struggling.  After Wessel pushed him to the surface, nearby boaters pulled him from the lake.

Authorities say Wessel was airlifted to a hospital in Wausau, Wisconsin where she was pronounced dead.

Janice Potocki, Wessel's sister, also swam out to save the boy and two other children who were having trouble in the water.  She says that Wessel saved the boys life, and called her "a hero."