A 12-year-old girl has been identified as one of the five students who were gunned down in Canada's second-deadliest school shooting as the gunman’s dark history came to light.

Jesse Van Rootselaar, 18, opened fire in the library at Tumbler Ridge Secondary School in British Columbia on Tuesday afternoon after killing his mother, Jennifer, and brother, Emmett, at their home, Royal Canadian Mounted Police said.

Kylie Smith, 12, was killed in the rampage, alongside two other girls and two boys, as well as an unidentified female teacher. More than two dozen others were also injured in the mass shooting.   

Lance Younge described his daughter Kylie as the 'light of their family' while speaking to CTV.

'She was just a beautiful soul. She loves art and anime. She wanted to go to school in Toronto and we just love her so much,' he said. 'She never hurt a soul.' 

An online fundraiser also describes Kylie as a 'beautiful, kind, innocent soul'.

Questions now remain about what may have driven Van Rootselaar to commit the heinous crime, as the Royal Canadian Mounted Police revealed firearms were confiscated from the boy’s home - but then returned.

The teenager began identifying as female at the age of 12 and had a series of mental health issues that caused police to respond to his home, the RCMP said.

He even stopped attending school four years ago at the age of 14 and at least once had to be 'apprehended for assessment' under the country's mental health act.

'Police have attended that residence in the past, approximately a couple of years ago, where firearms were seized under the Criminal Code,' said Dwayne McDonald, Deputy Commissioner of the British Columbia RCMP.

'I can say that at a later point in time, the lawful owner of those firearms petitioned for those firearms to be returned, and they were.' 

Van Rootselaar's mother, Jennifer, did not have a valid license for firearms at the time of her death. 

Those who knew Van Rootselaar said the gunman was a 'quiet kid' who was often seen 'sitting by himself in the corner'.

Amid the questions surrounding the shooting, though, Kylie's father said he wants the public to focus on the victims - and not the shooter.

'Let's stop giving this psychopath the recognition, because these kids were lost before they got to become teenagers,' Lance Younge pleaded with CTV.

'Let's put these pictures up, remember them and not this murderer.'

The distraught father told how he only heard from Kylie's 15-year-old brother when Van Rootselaar started shooting at the school Tuesday afternoon.

Ethan had been hiding in a utility closet at around 3pm local time and wanted to tell his family that he loved them.

But Younge did not know where Kylie was.

The last time he saw her, he said, was when she and Ethan entered school that morning. 

'I soaked in that moment watching them walk in the door together, for whatever reason,' he recounted. 'I didn't know it would be the last time.' 

Tumbler Ridge Secondary School has fewer than 175 students, and Younge said his family knows the victims all personally.

'They're amazing kids,' he said. 'All these families know each other, they grew up together.' 

'Hold your kids tight, tell them you love them every day,'  the heartbroken father then advised, warning: 'You never know, you never know.' 

As the family now struggle to accept the tragedy, they are raising money for Kylie's funeral and any associated travel costs.

Kylie's mother had recently moved to Vancouver Island after living in Tumbler Ridge for nearly 12 years.

'She hasn't seen her daughter in a few months and her son, Kylie's brother who just flew back up north from Vancouver Island will need his mom more than ever right now,' Kylie's aunt, Sharon Dycke, wrote.

'Kylie's dad and step mom are caring for her brother and step-brother right now, and their world, our world, has crumbled,' she added.

The GoFundMe has already raised over $20,000 for the family.

It concludes with Dycke saying: 'My heart aches for the other families involved and for the loss of their children. I am so sorry.

'To the families with children still in the hospital, keep fighting. We are sending you prayers.' 

Among those who were injured was 12-year-old Maya Gebala, who was shot in the neck and head. She was not expected to survive the night.

The girl's family has said she was hit by shrapnel during the shooting but it was unclear how she was hit and how much damage was done. 

'We were warned that the damage to her brain was too much for her to endure, and she wouldn't make the night,' Maya's mother Cia Edmonds said on Wednesday afternoon.

'I can feel her in my heart. I can feel her saying its going to be OK... she's here... for how long we don't know.

'Our baby needs a miracle.'

Edmonds said she also grieved for the six families whose children were killed at the school, and those trying to come to terms with the shooting.

'It was just a normal day. Our community is shattered,' she said.

'My heart bleeds for everyone who is trying to process this horrific string of events. Far too many are grieving already.'

An emergency alert was issued to Tumbler Ridge residents around 1.20pm local time Tuesday, warning of an active shooter in the area.

An urgent lockdown alarm sounded in the hallways shortly after 1.30pm, instructing students and staff to barricade the doors.

Darian Quist, a senior at the school, told CBC he was in his mechanics class when the lockdown began.

'For a while, I didn’t think anything was going on,' he said. 'I thought it was just like maybe a "Secure and hold" but once everything starts circulating, we kind of realized something was wrong.'

Quist said he and his classmates were then left to hide in fear for their lives for over two hours, which was only broken when cops eventually escorted them out of the classroom. 

He described the atmosphere in the classroom 'very nervous', which was made worse when he saw gruesome evidence of the carnage at his school sent to his cell phone.

'Once people sent me some photos, it definitely set in what was actually happening,' the student said. 

'They [the photos] were disturbing, just showing blood and things like that. That’s when it all really set in.'