Two Chicago gang members charged Monday in the death of a 15-year-old honor student mistook her and her friends for members of a rival gang and attacked the group in retaliation for a shooting that injured one of the men over the summer, according to police.

Hadiya Pendleton died after being shot in a park near the Chicago home of President Barack Obama on Jan. 29, just days after she performed during his inauguration festivities in Washington. Her death was among dozens of homicides in Chicago last month, but her background and ties to Obama thrust her death into the national headlines and helped put Chicago at the center of a national debate over gun control.

Police Superintendent Garry McCarthy said first-degree murder charges were filed against Michael Ward, 18, and Kenneth Williams, 20.

Pendleton, a popular high school majorette, was with a group of friends who took cover during a rainstorm under a canopy in a park about a mile from the Obama home on the city’s South Side. Police said a man hopped a fence, ran toward them and opened fire with a handgun before fleeing in a waiting car. Pendleton was struck in the back and died later that day. Two others were injured.