KATY, Texas -

A Katy ISD high school student is accused of bringing firearms on campus. The scare forced the evacuation of more than 3,500 students at Seven Lakes High School Monday.

According to district officials, the students were ushered out of the building and onto the school's athletic fields after learning of a "potential explosive device" in a backpack on the east side of the school.

Anxious parents waited outside Seven Lakes High in the 9200 block of South Fry Road on Monday afternoon as the Harris County Bomb Squad swept the school.

"I have a ninth grade student here, ninth grade daughter, so of course when I got the email, I raced down here, even though they told us not to," said parent Carrie Bilski.

As students were being dismissed for the day, officials confirmed that the device turned out to be a "zip gun," which is a device altered to propel an object designed to cause harm

Thomas Barfield, a 19-year-old student at the school, was arrested and charged with possession of a prohibitive weapon. District officials also said a firearm was found in the trunk of Barfield's vehicle parked on campus.

"It's just weird to think that someone at your school would actually do this. And it's not very comforting," student Zoe Heeter said.

Parents and students said they're relieved now that a suspect is in custody.

"I feel a lot better. I feel a bit safer now," said student Sara Liuhoff.

Katy ISD said all official after-school activities had to be been canceled Monday.

The investigation is continuing off-campus as well. Local 2 has seen a lot of federal and county law enforcement officers, along with Katy ISD police officers, file into the gated Canyon Gate subdivision where authorities are searching a home.

Local 2 has not been given any specific information for what investigators are looking for. However, firefighters, arson investigators, sheriff's detectives and ATF and FBI agents have been steadily going in and out of one house.

Neighbors who live nearby said they're not being given much information either. However, neighbors said they have been told there is no danger and no one is being asked to evacuate.

Meanwhile, Katy ISD officials said school will resume to normal on Tuesday. Students are asked to report to fourth period homeroom.

Barfield is expected to face a Fort Bend magistrate judge Tuesday morning.