PENNSYLVANIA - Officials say the teen charged in the Pennsylvania high school attack used common kitchen knives and probably worked alone.

Alex Hribal, 16, used two kitchen knives when he stabbed and slashed his way through the halls of Franklin Regional Senior High School, police say.

A total of 21 students and a security guard were wounded before an assistant principal and a student tackled Hribal.

At least five students are in critical condition now.

Police do not think anyone was specifically targeted. However, the FBI has taken the computer from Hribal's home.

Hribal is being charged as an adult with attempted homicide, aggravated assault and weapons possession on school grounds. 

Hribal’s father has offered prayers for the victims.