DIXON, Ill. (AP) — The mother of the teenager charged with firing shots at a northern Illinois high school says he was ostracized and bullied by classmates.

Authorities say 19-year-old Matthew Milby suffered non-life-threatening injuries Wednesday when he was shot by a school resource officer outside Dixon High School. Police say Milby fired several shots on school grounds as seniors rehearsed for graduation. No one else was injured.

Julie Milby told reporters her son was recently beaten up, other students stole from him and he was kicked off the football team for smoking marijuana. She says he was supposed to graduate Sunday.

Dixon senior Brianna Johnson says Milby seemed nice but was recently angry all the time.

Classes were canceled Thursday at the high school about 80 miles (130 kilometers) west of Chicago.