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Police said they received reports of a student possibly bringing a weapon to the campus, located on Fairmont Parkway.
Pasadena ISD told ABC13 that one student was arrested after school police discovered a hidden firearm.
Officers believe the student hid the gun after realizing the police had come to the school.
Authorities said they don't believe the student had intentions of using the gun. It's unclear if any charges will be filed.
SkyEye was above the public school Tuesday afternoon, where several district police officers' patrol vehicles could be seen parked outside.
"Please know we take these situations very seriously, as the safety of our students and staff is always our top priority," Pasadena ISD said.