PERRY HALL, Md. — A 15-year-old student has been charged as an adult with attempted first-degree murder in a shooting on the first day of classes at a Baltimore County high school, authorities said today.

Robert Wayne Gladden, Jr., also was charged with first-degree assault and was being held without bail at the Baltimore County Detention Center, Baltimore County police said. No hearing has been scheduled for Gladden and the state’s attorney’s office did not know if he had legal representation.

Classes resumed today at Perry Hall High School amid a low-key police presence and about 150 students turned out for a prayer vigil organized by churches on the grounds of the school.

Authorities say the student opened fire Monday at the high school, allegedly getting off two shots and wounding a classmate before being rushed by teachers. The 17-year-old victim remains in critical condition at Maryland Shock Trauma Center, a hospital spokeswoman said.

The suspect’s father spoke to a reporter at his home that evening and said his son was the shooter. When asked about a motive for the shooting, the father indicated his son had been bullied.