WASHINGTON, April 9 -- Nineteen students and one adult were injured Wednesday morning after a stabbing spree inside a high school in the U.S. State of Pennsylvanian at the start of the school day.

The suspect attacker, identified as a 16-year-old male student at the school, was taken into custody by police shortly after the incident. And seven seriously injured, all students aged between 15 to 17, have been taken to hospital, according to the report of U.S. Cable News Network.

The Franklin Regional High School was on lockdown, and students were being kept there for safety. The school is located in Murrysville district, where about 3,600 elementary and middle school students live and study on the same campus.

No fatalities were reported so far, but doctors said there are several suffering from life threatening injuries, CNN reported.

Local police are conducting investigation on the cause and details of the incident.