The stabbings happened around 8:15 a.m. at Antietam Middle-Senior High School, according to a dispatcher at the Berks County Communications Center.
A 16-year-old girl was taken to Reading Hospital with cuts to both hands, hospital spokesman William J. Rudolph Jr. said. Doctors also treated a 15-year-old girl with a small wound to her upper back and a 14-year-old boy with a small wound to his upper right arm, he said.
The wounds were not life threatening, officials said.
The Reading bomb squad and numerous police agencies were called to the scene, said state police Lt. Thomas G. McDaniel said. Antietam School District officials could not immediately be reached for comment.
The school enrolls students in grades seven through 12. It is located in eastern Pennsylvania, about 65 miles west of Philadelphia.