As new details emerge about how a serious situation unfolded at a Richmond high school earlier this week, parents are concerned about the way the incident was handled.

A series of threats issued on Monday resulted in students being shut in the classrooms of Robert Alexander McMath Secondary School on Tuesday, leading some to wonder why students were allowed back in the building in the first place.

The situation began Monday afternoon, when Richmond Mounties were informed that the name of the school's Wi-Fi network had been changed. The school called it an attempt to "anger and scare" students and staff, and said that police felt the threats were not serious at the time.

Parents were sent an email from the principal about the incident, but they were told it was safe for kids to come back to school the next day.

CTV News has since learned that the email said "unsettling statements" were being displayed when accessing the Wi-Fi. The district later clarified that the networks weren't compromised, but that a connection point called a hot spot had been created, possibly with a cellphone.

The principal's email said he was thankful that the statements were flagged immediately by students and staff.

"Through their actions, we were able to quickly activate our School District’s Technical Services Department and our School Liaison Officer (RCMP) to ensure our school site was safe," Neil Kamide wrote.

"For the benefit and knowledge of all members of our school community, the police have reviewed the posts and feel the motivation behind this action is not a serious threat."

Kamide added that investigations were ongoing, the wireless network was being monitored and that anyone found to be involved could be charged. He suggested parents to have conversations with their children about what happened, and encouraged that anyone with more information contact the school's administrators.

"Our school is open and school will resume as per normal tomorrow, Tuesday, May 30th," the email said.

While some kept their children home the next day, many students returned to school. But when they arrived, they were told they'd have to stay in their first-period classrooms for the day as officers searched lockers, belongings and cellphones.

"We weren't allowed to leave. We had to be escorted places," one student told CTV.

A youth was arrested later in the day, then students were dismissed before 3 p.m.

School board chair Debbie Tablotney said that what happened was the district was made aware that there was a heightened threat present just as students were arriving at school. The board was not aware of further threats until that moment, which is why they'd sent an email telling parents it was fine for students to come in the next day.

"There will be a debrief on the situation," she said.

The second threat was an online message, and while officials have not confirmed the details of the threat, one student said it referenced a shooting.

Police returned to the school on Wednesday to provide a presence as students returned to regular classes, and also to follow up on the ongoing investigation.

With a report from CTV Vancouver's Maria Weisgarber