Three William Penn High School freshmen were arrested for bringing weapons, including a 9mm handgun, to the school in New Castle on Wednesday.

The three were caught after a fellow student saw an Instagram photo of two of the students posing with a gun in one of the school's bathrooms, and then alerted school administrators. 

Colonial School District Spokeswoman Lauren Wilson said upon learning about the photo, high school administrators immediately removed both students in the photo from their classrooms and called the school's Student Resource Officer, a state trooper, to assist.

Delaware State Police said when school staff searched the 16-year-old boy's bookbag, they found an unloaded, realistic-looking, gas-powered pellet gun. Inside the 15-year-old boy's book bag, they discovered an unloaded 9mm handgun.

Further investigation revealed a third student, another 15-year-old male, had originally brought the gun to school. That student was removed from class and school leaders found two magazines in his book bag; one magazine was empty, the other contained six 9mm rounds.

Wilson said all three students were removed without incident. 

Superintendent Dr. Dorothy Linn applauded the student who showed the Instagram photo to the school administrator and praised her staff for taking swift action. That being said, she said she is deeply disturbed by the incident. 

"The safety of our students and staff is a top priority. It is disheartening to know that these three students made such poor choices, especially at a time when the majority of students at William Penn are doing the right thing and don't deserve the black eye that this incident will bring," said Linn, who added her district is fully cooperating with police. 

The three teenagers were charged with weapons-related offenses and were committed to the New Castle County Detention Center on secured bail.

Wilson said the students also face serious punishment from the district.