This is a breaking news story. Check back for updates.
UPDATE 10:59 a.m. EDT: Mark Rubino, chief medical officer at Forbes Hospital, described the types of injuries of the victims who were taken to the facility.
"The wounds were all knife wounds. Most of them were to the lower abdomen and they seemed to almost have a pattern," he said, noting that the victims were stabbed in the right abdomen.
Rubino said three patients have severe injuries and are still in the operating room. Two of those patients are in critical condition but have stabilized. Another five patients are being evaluated; three or four have superficial wounds and "will be fine," he said.
UPDATE 10:43 a.m. EDT: Murrysville Police Chief Tom Seefeld said the suspect had injuries to his hand and "is being medically treated." He said the school's fire alarm was pulled during the incident, which he suggested prevented more students from being wounded.
Police "saw a chaotic scene outside with people running everywhere," he said, adding that "a good thing was done" by pulling the fire alarm.
Seefeld said four of the victims had life-threatening injuries.
He said police were checking up on reports of a threatening phone call between the suspect and one of the students before the stabbing occurred. Seefeld wouldn't get into reports that said the suspect may have been a victim of bullying.
UPDATE 10:38 a.m. EDT: Stevens confirmed that the suspect is a 16-year-old sophomore at Franklin Regional High School, but gave no other information about the teen at a news conference. Stevens said 19 students and one school staff member were stabbed by the suspect.
"No motive has been determined on the incident," he said.
UPDATE 10:19 a.m. EDT: An assistant principal at the school and a security guard were credited with disarming the suspect of two knives, CBS Pittsburgh reported on its Twitter account.
UPDATE 10:15 a.m. EDT: The suspect has been identified as a student at Franklin Regional High School. According to one report, he's a sophomore at the school.
UPDATE 9:51 a.m. EDT: Adults are among the people injured in the stabbings, according to WXPI reporter Peggy Finnegan. She also reported on her Twitter account that the serious injuries include puncture wounds to the trunk and torso. A doctor at Forbes Hospital told Finnegan that there are seven victims with life-threatening injuries.
UPDATE 9:12 a.m. EDT: Stevens said the suspect who is in custody is being interviewed by Murrysville police, WTAE reported. Meanwhile, U.S. Sen. Pat Toomey, R-Pa., sent out the following tweet about the stabbings:
Awful news out of Franklin Regional High School. Please pray: http://t.co/haSJFrjobs
â€” Senator Pat Toomey (@SenToomey) April 9, 2014
At least 20 students were injured during stabbings at a Pennsylvania high school on Wednesday morning, according to media reports.
Authorities were contacted about the stabbings at Franklin Regional High School in Murrysville around 7:13 a.m. EDT by a school resource officer, CBS Pittsburgh reported. An emergency management official told the station that 20 students were injured in the stabbings, including four with serious wounds.
One person is in custody, an emergency management spokesman, Dan Stevens, told Pittsburgh television station WPXI.
A statement posted to the Franklin Regional School District website didn't go into detail about the stabbings, but alluded to a “critical incident” and said the elementary school will be shuttered for the day.
“A critical incident has occurred at the high school. All elementary schools are canceled, the middle school and high school students are secure,” the statement said. “Additional information will be released as soon as possible. Please keep our campus clear of traffic.”
A witness told CBS Pittsburgh that the stabbings occurred in the science wing of Franklin Regional High School. According to WPXI, one report said a person ran through the school stabbing students with a knife or other sharp object, although that report hasn't been confirmed by police.
“One of the children that pulled the alarm, my daughter said, after the incident happened to clear the school. She reported to me it was a 10th grade student,” parent Tim Graham told CBS Pittsburgh.