Twenty people were injured, at least nine seriously, when a student at a Pittsburgh-area high school went on a stabbing rampage earlier today.

The suspected attacker, who was not identified, was in police custody, said Reuters.

Seven students between the ages of 15 and 17 and one adult were admitted to Forbes Regional Hospital in Monroeville, Pennsylvania, with stab wounds, Reuters said.

The attacks took place in several classrooms and hallways as the school day began at Franklin Regional High School in Murrysville, 20 miles east of Pittsburgh, Reuters said. Three of the patients admitted were in surgery and all eight were in critical condition, Reuters said.

Pennsylvania Governor Tom Corbett said he had ordered state police to help local law enforcement respond to the incident.