PORTLAND, Ore. (KOIN) – The FBI is investigating a serious bomb threat that caused an evacuation at a Tualatin middle school Friday morning after a viral video of an assault between two students last week.

Hazelbrook Middle School staff say they began receiving email and phone threats earlier in the week, but the most recent included a bomb threat prompting federal involvement.

“Given the specificity within that email, against not just the school but also against specific staff and their families, and that is correct, that this one had potentially more concerns for law enforcement and so being prudent and ultimately cautious, we said we are going to send students home,” Tigard-Tualatin Superintendent Sue Rieke-Smith said.

The email, also sent to KOIN 6 and other media outlets, warned to send kids home because the school had been rigged with explosives and there would be a shooting. In response, law enforcement searched the school to ensure security for school leaders.

The threat also sparked concerns for the safety of a specific student who can be seen in footage of the assault that went viral on social media. The middle school has since received a barrage of hate mail focused on the perceived gender identity of that student, who they say had initiated the attack.

According to those behind the email, the assailant had not received any consequences following the attack. The night after the bomb threat, officials announced the student was arrested on charges of fourth-degree assault and harassment.

Tigard-Tualatin Superintendent Sue Rieke-Smith told KOIN 6 that staff had responded in the hall and restrained the attacker until nearby school resource officers took the student away.

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“Students don’t check their constitutional rights at the door, but they also have responsibilities to follow the law. And when they do not follow the law, regardless of protected class, if they have that designation, they still are held accountable,” Rieke-Smith said. “And that’s the reason why it is now in the hands of law enforcement and being prosecuted as a criminal act.”

The students involved, including the one who took the video, are minors. No other details will be made public.

Law enforcement has yet to confirm whether they have tracked down the source of the bomb threat. The case remains under investigation.

On Friday evening, officials with the Washington County Juvenile Department, Tualatin police, and the Tigard-Tualatin School District sent a joint press release addressing the incident:

In a TTSD State Safety and Wellbeing Forum with district and school leaders this week, parents appeared fired up – with one getting up and leaving as the superintendent said, “We don’t deny anyone their right to an education. And the vast majority of them have a marvelous day but there are those who are not happy with their day and they make it difficult and frightening for others.”

The district says they partner with law enforcement when it comes to incidents like assault, but are working on extra measures like adding more cameras to halls. They also asked that parents work with their individual schools on concerns.

According to district officials, there are more than 1,000 students enrolled at Hazelbrook Middle.

Stay tuned with KOIN 6 as we update you on this developing story