Twenty people were injured after a stabbing at Franklin Regional High School in Murrysville, Pennsylvania.
The school is 17 miles from Pittsburgh.
As many as 20 people may be injured.
The attack occurred at 7 AM this morning. A male student was arrested.
ABC reported:
At least nine people were injured after a stabbing spree inside Franklin Regional High School in Murrysville, Pa., at the start of the school day, emergency management officials told ABC News.
No fatalities were reported, Westmoreland County emergency management spokesman Dan Stevens told ABC News. However, the extent of the injuries was unclear.
The breakdown of injured and whether they were students or staff was not immediately known, but two hospitals reported nine patients ranging in age from 15 to 60.
Stevens said the alleged stabber, whose identity has not been released, was in custody.
Te victims range in age from 14 to 17. Many suffered a variety of injuries. Four were airlifted to area hospitals in serious condition. 
One student at the school said several students in the science wing were attacked. (WTAE)
The Franklin Regional School District website posted this:
A critical incident has occurred at the high school. All elementary schools are cancelled, the middle school and high school students are secure. Additional information will be released as soon as possible. Please keep our campus clear of traffic.
Hospital officials said thee patients range in age from 15 to 60 years old.
UPDATE: FOX News just reported a sophomore was arrested
