As 13-year-old Gabriel Clarke recovered in a hospital bed after being shot Friday while walking to choir practice in Roxbury, classmates ­returned to a school guarded by police and shaken by the violence.

“Everybody knows what happened, and we were talking about it in school,” said ­Carolina Alcantara, a seventh-grader at the Curley K-8 School in Jamaica Plain. “A lot of us are sad, because a lot of us know him and we can’t believe that he was shot.”