The 13-year-old boy accused in the attack at Antietam Middle-Senior High School is due in juvenile court for a detention hearing on Friday, Central Berks Regional Police Sgt. Ronald Uczynski said.
The boy faces four counts of aggravated assault, one count of recklessly endangering another person, one count of causing and risking a catastrophe, one count of criminal intent to commit criminal mischief and possession of a weapon on school property, Uczynski said.
He is being held at the Berks County Juvenile Detention Center.
Witnesses said the boy, wearing a dark trench coat and listening to his MP3 player, burst into an English class Wednesday and began slashing at students with a knife, flipping desks, throwing books and lighting firecrackers.
Three students suffered minor stab wounds before the boy was subdued by school officials.
Police said the boy brought to school a small can of gasoline, a water bottle filled with torch fluid, firecrackers, knives and face masks to keep out fumes.
The school reopened under tight security on Thursday, with police searching every student with a handheld metal detector.
Students could use only one entrance to get inside the building.
Police Officer Ray Serafin said all bags were searched. Police confiscated pocket knives and other minor contraband, but nothing serious.
"Every student was screened prior to entering the building," Serafin said. "All went well."
The school in Lower Alsace Township, about 60 miles northwest of Philadelphia, enrolls 540 students in grades seven through 12.
