PORTLAND, Ore. (KOIN) — Students in one class had their backpacks searched Friday at Highland Park Middle School in Beaverton.

A student reported overhearing another student talking about bringing a bomb or gun to school. That student has not been identified at this time, but the investigation is ongoing.

At a meeting Thursday night, Principal Curtis Semana was asked why they aren’t searching all students. He explained it’s because they are limited by the law since the threat is limited to that particular classroom.

“We can’t require or force a search without reasonable suspicion of a specific individual or a small group of individuals.,” said Semana.

There was also a way for students to avoid a search.

In a letter to parents obtained by KOIN 6 News the district wrote “If students do not give permission for a search, we will bring their backpacks to the office to be held through the end of the day, and their parents/guardians will be called.”

A spokesperson for Beaverton School District said there’s been rumors at several schools, including Highland Park, about potential threats in the past week.

The principal of Aloha High School sent a message Thursday night saying an anonymous threat was made in an online chat which included at least one student from the school.

Each case has been investigated by the district’s Public Safety, Beaverton Police Department and Washington County Sheriff’s Department. Additional school resource officers are on duty Friday.

Officials have not found any of the threats to be credible, according to the district.