It occurred around 11:40 a.m. at William Penn High School on the 700 block of East Basin Road in New Castle.
[Ads /]
According to police, a school resource officer was alerted to a potential gunshot inside a second-floor restroom.
The resource officer found signs that a round struck the interior of the restroom, police say.
State police say further investigation revealed a suspect ran from the back of the school towards the football stadium.
The school was placed on lockdown for about an hour while investigators searched the building.
Investigators canvassing the area discovered a Glock handgun outside the school.
[Ads /]
No injuries were reported.
Police say the number of suspects involved is still being determined.
William Penn High School will be closed for the remainder of the week.
A message posted on the school's website reads:
"To allow for the DSP to conduct a thorough investigation, school will be closed for ALL William Penn students (including N3) [Wednesday,] January 11 and Thursday, January 12. All before and after-school activities, sports and events scheduled during these two days will be postponed and rescheduled for a later date.
[Ads /]
"Friday, January 13th is a Professional Development Day with no classes scheduled for students. We will resume school for students on Tuesday, January 17th after the MLK Holiday.
"The safety of staff and students remains our immediate priority and by allowing for this break it provides officials with the time to properly investigate and gives everyone time needed to regroup after today's events."
The school says there will be extra support available for any students who need it when classes resume.
"While we are disappointed that this unfortunate incident occurred, we are thankful no one was injured and that students and staff responded quickly to the safety protocols put in place. We will get through these unsettling times together and will keep families updated," the school said.
Troopers are asking anyone who witnessed this incident to contact Detective R. Strecker at 302-834-8413.