We're getting our first details this morning about the 16-year-old Pennsylvania teen who is accused of stabbing 21 students and an adult yesterday at a high school outside Pittsburgh. Fox News has confirmed that Alex Hribal was being charged with four counts of attempted homicide, 21 counts of aggravated assault and one count of possessing a prohibited weapon on school property.

Hribal's father, Harold, made a brief statement, saying his prayers go out to those who were hurt and hopes they recover as quickly as possible.

Authorities are looking into a phone call involving Hribal Tuesday night in which he may have threatened another student.

One student described Hribal as small and skinny, saying he did not talk much. Some kids say Hribal was a victim of bullying. Authorities say Hribal, who is being held without bail, has not been talking since his arrest.

Franklin Regional Senior High School assistant principal Sam King is being hailed as a hero for tackling Hribal and stopping the attack. King was treated at a hospital, but did not get stabbed. Five students are still in critical condition, but their injuries are not said to be life-threatening.

Read more on the incident and investigation at FoxNews.com.