Hadiya Pendleton was killed in a park close to the Obamas' home on Chicago's South Side. Police say a gunman hopped a fence and opened fire on a group of young people, killing the drum majorette. No arrests have been made.
Pendleton's death brought renewed attention to Chicago's homicide rate and the debate over gun violence in America.
The White House official spoke on condition of anonymity because the first lady's travel plans had not been formally announced.