The shooting victims, a 31-year-old male teacher and a 17-year-old student, were taken to area hospitals with serious but non-life-threatening injuries.
Boston police say the shooting happened at about 5:40 p.m. at TechBoston Academyin the Dorchesterneighborhood.
The victims were preparing for a school event when someone opened fire on them in the parking lot, reports WCVB-TV.
No arrests had been made as of Wednesday morning.
Boston Superintendent Brenda Cassellius said no classes will be held Wednesday at TechBoston Academy.
TechBoston Academy offers a college prep curriculum for grades six to 12.