Starr gets several different reactions from people when they discover she witnessed Khalil's death.
People around her neighborhood are typically the most empathetic. They understand what it must have been like to see him die and feel the personal danger Starr herself was in. Still, those in Starr's immediate community then often link Khalil's death to their own feelings about the larger issue of police violence in their neighborhood.
Starr's family worries the most about her and does the most to try to protect her. Still, they also prioritize keeping a routine and make sure she goes back to school and continues her own life as soon as possible after the tragedy.
When people at school discover that Starr witnessed Khalil's death, the reaction is very different. Many of Starr's classmates have developed a perception of Khalil as a "thug" through seeing media coverage of the incident. This leads to much less empathy or support. Some of Starr's classmates even feel that Khalil "deserved" what happened, so they provide little comfort to Starr in the wake of her loss and trauma.
Overall, everyone responds to Starr's experience with their own interests close at hand. For her family, that interest is protecting Starr. For her neighbors, the interest is protecting their neighborhood. For her classmates, the interest is condemnation of the "thug" they've seen depicted on TV.