One of the two students who were stabbed at an Abbotsford high school early Tuesday afternoon has succumbed to her injuries. 

Police Chief Bob Rich announced the tragic development at a news conference after dark, offering his condolences to the loved ones of the victim, whose name hasn't been released.

"We are heartbroken for the family that lost their daughter. Words can't express – I'm just so sorry," Rich said.

The extent of the other girl's injuries has not been confirmed, but police said she remains in hospital in stable condition.

Both of the victims were attacked inside Abbotsford Senior Secondary School, prompting calls to police shortly after 2 p.m.

Const. Rich said officers arrived at the school within minutes, and found that a suspect had already been subdued at the scene by staff members. Students and employees were also working together to render first aid to the victims.

"I cannot tell you very much about the young man that we have in custody," Rich told reporters. "It appears he is not a student at this school, and it is possible he has no connection to these two students."

The suspect's identity has yet to be determined, and investigators are still trying to understand what led up to the disturbing attack, which shocked the Fraser Valley community.

After police, firefighters and paramedics arrived at the school, the two girls were rushed to hospital, at least one of them being transported in an air ambulance, along with members of their families who had been contacted by school staff.

Officers then locked down both Abbotsford Senior Secondary and the adjoining Abbotsford Middle School, as an Emergency Response Team checked for any more potential victims or suspects. None were found.

The lockdowns lasted well after the end of the school day, leaving many worried parents anxiously waiting to learn more about what had happened.

"It's terrifying," one woman told CTV News while standing behind police tape at the school. "We know our children are in a locked classroom, we have no idea what's going on."

Parents were eventually able to reunite with their children at a staging area at the Abbotsford Arts Centre.

Shortly after the attacks, disturbing video emerged on social media appearing to show one of the girls and the suspect. A young man can be seen standing over a girl and seemingly stabbing her in the midsection before dropping a knife and then backing away.

At the Tuesday news conference, Const. Rich asked that people not pass the recording around.

"Out of respect for the family we are asking that this video not be shared further," he said.

Anyone with information on either stabbing who hasn't spoken to police is asked to contact the IHIT tip line at 1-877-551-4448, or Crime Stoppers at 1-800-222-8477 to remain anonymous.

With a report from CTV Vancouver's Shannon Paterson