BEAVERTON, Ore. — The Beaverton School District had extra staff and sherrif's deputies on hand Monday morning as students returned to Stoller Middle School after a lockdown Friday had them sitting quietly under desks for hours Friday.

Maggie Lu, a sixth grader, spoke to KGW News as she was walking to school after her mom gave her the go-ahead to attend class.

"I'm not too scared, so long as nothing else happens, like we'll have to go into lockout again," she said.

Maureen Wheeler, with the Beaverton School District, said the school wouldn't be opening its doors if it wasn't safe.

“We wouldn’t be able to operate if law enforcement said it wasn’t safe," she said. "So I think that’s number one, and I think we’ve got great supports today. Your fears are understandable but we also have to move forward and we’re doing all the right things to make the teaching and learning happen every day.”

However, some parents who spoke to KGW on Sunday said they were hesitant to send their kids back to class.

“We thought that the investigation would've gotten further over the weekend and we would have more answers now and we're scared to bring them back tomorrow because we don't know what's going to happen,” parent Lindsey Carr said Sunday.

Around 12:20 p.m. Friday, several middle school administrators received an email threatening violence.

The district said based on what was in the email, deputies were concerned a possible suspect was already inside the building and planning to do harm.

Deputies searched room by room Friday because of that, but nothing was found in the school. Students were released about 4:45 p.m.

Isabella Taylor is a seventh grader at Stoller Middle School and described the scary few hours.

“An announcement came back on and said we are now in lockdown and the teachers were like, 'Get under the tables, don't move, don't talk,' so we were basically still for two hours straight,” she said.

Videos of the lockdown show students sitting in silence in the dark under desks.

Lu said she vividly remembers the confusion on Friday.

“The classroom was really dark because we had to turn off a lot of lights and we had to crouch in a corner and we actually had an emergency bucket a lot of students used,” she said.

In one video, deputies walk through the door with guns drawn. Taylor said some students started crying for joy when the deputies walked in because of how scared everyone was before seeing them.

“Everybody was praying, hoping that nothing would happen, and people were crying and texting their parents basically if anything happened, [to say] goodbye," she said.

Over the weekend, the district said it worked with law enforcement to search the entire school including classrooms, common spaces, backpacks and lockers. They also brought in extra custodial staff to thoroughly clean the building.

On Monday, there were an additional 30 to 40 staff members on site along with Washington County sheriff's deputies, counselors, and psychologists to speak with staff, students, and parents. Five counseling centers were set up at the school for students and adults.

But, even with the added staff, some, like Taylor and her mother Lindsey Carr, were still uneasy.

“If somebody was held accountable for the email and we knew where it came from, so we know that tomorrow when we bring our kids, that person's not going to be here, because we really have no clue and that's not OK,” Carr said Sunday.

Another parent, Zhrkur Ren, said she's worried, but she talked through the situation with her son, a sixth grader, before he returned to school Monday.

"I am concerned, but I think the best thing to do is have a good conversation with kids," Ren said. "Just trying to make sure he's not scared, he feels safe too, and [that] he knows the protocols, what to do and when he needs to be quiet. It's hard for a sixth grader."

The Washington County Sheriff’s Office said this investigation is a top priority. It is working with the IT department at the school to figure out who sent the email.

“I know there are going to be a lot of people here keeping an eye out, but I'm still really shaken up about what happened that I just don't know,” Taylor said.