Antian Hardmon, 25, was fatally shot during a barbecue in Chicago’s Fuller Park neighborhood on September 28, 2015. The gathering of about 30 people had been held to commemorate someone who died in a crash years earlier. Around 12:10 a.m. gunfire erupted from an alley; Hardmon was struck in the head and died shortly after being taken to Mount Sinai Hospital.

Two other people were killed that night: 22-year-old Ayanna Northern and an unidentified 30-year-old man. A 24-year-old woman and a 36-year-old man were also injured in the shooting. Reports say two men were arrested and charged in connection with the killings, including multiple counts of first-degree murder, aggravated battery with a firearm, and attempted murder.

What details about that night or the people present might help explain how an outdoor memorial became so deadly?