As many as 20 students were hurt in a stabbing incident in a Pittsburgh area school. The AP is reporting that four were believed to be seriously injured.

Westmoreland County emergency management spokesman Dan Stevens told the AP not all of the 20 injured were cut by the knife, though most were. Some suffered scrapes and cuts in the ensuing panic at Franklin Regional High School in Murrysville this morning.

Stevens says it doesn't appear any students suffered life-threatening injuries. He says all the injured are between 14 and 17 years old.

The suspect, a male student, is in custody and is being questioned by police.

It's not certain, at this hour, what kind of knife was used or what the attacker's motives were.