Seven Lakes High School in Katy, Texas was evacuated Monday because police “learned of a perceived threat on campus.”

Students were escorted to an enclosed area on the school’s athletic field after a suspicious device was found in a backpack. About an hour later, officials revealed the item could be a potential explosive device. The county bomb squad and bomb technicians from the FBI secured the device and swept the school, which was ultimately cleared.

The device turned out to be a homemade zip gun: a device that is designed to propel an object and cause harm. These weapons are often constructed out of pipes and can be used to fire nails.

The student responsible for bringing in the zip gun, Thomas Scott Barfield, was taken into custody and charged with possession of a prohibited weapon. Officials also found another weapon in the trunk of Barfield’s vehicle.

A student who knows Barfield wasn’t too surprised at the findings.

“He was kinda a pyrotechnic if you know what that is,” said Josh Rubin, a senior at the school, in an interview. “He liked to make things with fire and all that. He is honestly a nice person if you just talk to him, but he would be a person I would expect would do something like this.”

Students were dismissed at 1:30 pm and were allowed to be picked up by a parent or walk home. Bus transportation was also offered. Students who had their vehicle keys with them were able to leave. Those who had to go back into school to retrieve keys or other possessions were not able to do so immediately.

Classes were to resume as usual on Tuesday.

About 3,800 students attend Seven Lakes High School. Katy is around 25 miles west of Houston.

Image via Seven Lakes High School website