(CNN) -- At least 20 students were injured Wednesday morning in a stabbing incident at Franklin Regional Senior High School in the Pittsburgh area, said Dan Stevens, an emergency management agency spokesman.
Four people were flown to hospitals by helicopter, he said.
Dr. Chris Kaufmann at Forbes Regional Hospital in Monroeville, Pennsylvania, spoke to CNN on air. He said the facility is treating seven teens with stab wounds to their torso, abdomen, chest and back areas. He said that the injuries were “quite serious” and that “some are clearly life-threatening.” An adult is also being treated there, he said.
A message on the Franklin Regional School District’s website said all of its elementary schools were closed after the incident, and “the middle school and high school students are secure.”
Stevens said a suspect was in custody.
Information on what led to the stabbings and the conditions of the injured were not immediately released. The students range in age from 14 to 17, Stevens said.
The school is in Murrysville, about 15 miles east of downtown Pittsburgh.
Students were being released to their parents, Stevens said.
CNN first learned of the stabbings on Twitter.