Five of the victims were found dead in the library and a sixth in the stairwell. Van Rootselaar died from a self-inflicted gunshot wound minutes before police arrived at the scene.
Maya and another girl, Paige Hoekstra, were airlifted to a children’s hospital in Vancouver, where they are being treated for life-threatening injuries.
Krysta Hunt, Maya’s aunt, said her niece has undergone surgery and remains in “extreme critical condition” with a bullet still lodged above her left eye and another in her neck.
Maya’s chances of survival are uncertain, she told the Canadian outlet Global News.
Hunt said: “She had surgery yesterday to try and repair the brain bleed and they’re waiting to see how she responds to that.”
Her aunt praised Maya’s friends who spotted Maya moving her fingers and rushed over and carried her out of the library to summon help.
“[Maya] tried to lock the door of the library from the shooter to save the other kids and then she tried to lock it and then ran and hid under a table and [got shot],” Hunt said.
She described Maya, a keen hockey player, as a “feisty little girl who is brave and strong”.
“You don’t think something like this is going to affect your family,” Hunt said. “It’s insane.”
On Wednesday night, Maya’s mother, Cia Edmonds, said doctors had warned the family that the damage to her brain was “too much to endure”.
She wrote on Facebook: “I can feel her in my heart. I can feel her saying it’s going to be okay.
“I cannot reply to the mountain of messages we’ve received, but know we are so grateful for all the love and support, she’s here for how long we don’t know.”
“It was just a normal day. Our community is shattered. Our baby needs a miracle.”
An online fundraising page to help with medical expenses for Maya has so far received C$257,000 ($312,780).
Paige is also in critical care at the hospital and has undergone surgery.
Her older brother, Nicholas, said: “We’re still trying to wrap our heads around it. It all happened so fast.
“Watching someone you love go through something like this is something you can’t really prepare for. We’re scared, we’re hoping, and we’re just taking it one moment at a time.”
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