Upper Dublin High School entered lockdown this morning and police converged at the scene after a student's umbrella was mistaken for a rifle.
A science project involving an umbrella that looked like a unidentified rifle on a security camera caused the lock down, and prompted police to race to the scene.
Some parents pulled their children from classes.
The incident started shortly after 8:30a.m., said Deputy Chief Lee Benson. Four male students were seen on a security camera with what looked like a "long gun."
As a precaution, the school was lockdown as police and administrators identified the student and what class they were scheduled to be in at the time.
With weapons drawn, police entered the classroom and called out the name of the student with the umbrella.
"He (the student) quickly stood up," Benson said. The other three students were in the same class. They were still being questioned by detectives, he said. No charges were expected to be filed.
Officials had few details on the project, which they said was designed to "stimulate the human immune system protecting the body."
Benson said it was "poor timing" on the students' behalf to carry out the project in the days after the Newtown tragedy.
Bob Schultz, assistant superintendent said the boys parents were notified. He was very comfortable with the actions taken by the police.
Superintendent Michael Pladus sent a district-wide robocall there was nothing to the initial report of a rifle present in the school. He also sent a district-wide email.
"This morning, students were held in their 1st period classes as the police department and administration investigated what appeared to have been a suspicious event. The investigation revealed that it was nothing more than a student with an umbrella," he wrote. "Classes have resumed, and all students are back in class."
The incident happened as many were still on edge in light of the shooting rampage Friday in Connecticut.
A student inside the school, said via text during the lockdown, that: "cop cars are everywhere-something is happening."
Parents could be seen walking with the arms around students as they left the school shortly before 10 a.m.
Adam Borisoff, 14, was in his second period swim class when the announcement from the principal told the school to lockdown.
"This is not a drill," Borisoff said they were told. He and others were "frantic" as they retreated to a locker room.
Donny Borisoff came to get his son and was told that a student had walked past security cameras carrying the umbrella slung over his shoulder like a gun.
Borisoff said in light of events in Newtown he would rather have his son home where he could relax.
Another parent, Tony Davis, 53, received a text during the lockdown from his freshman son that read "Dad this is real."
Davis, an academic counselor at Montgomery County College came to the school but did not take his son from class.