TORONTO - The swine-flu death of an otherwise healthy hockey-playing teen came without warning and should serve as a lesson to parents to keep a close eye on their ill children, the boy's grief-stricken father said Tuesday.

Paul Frustaglio said it took barely more than a day for the H1N1 flu virus to kill Evan -- his "best friend" -- who turned 13 last month, a fatality that public health officials called rare.

"He fell so quickly," Frustaglio told The Canadian Press. "I was watching him. I was there when he died."

Evan's death Monday came on the same day health authorities across Canada began rolling out a vaccination program against H1N1.

The teen would not have been considered a priority for the flu shot because he wasn't in a high-risk group.

The Grade 8 student began feeling ill over the weekend during a hockey tournament. His symptoms included fever and some vomiting.

His dad took him to a walk-in clinic on Sunday afternoon, where he was seen and sent home with advice to take over-the-counter medication.

The family felt confident it was a simple case of flu that would soon pass.

That seemed to be happening. By Monday morning, his fever had broken and he was no longer nauseated. The family thought he was on the mend.

Evan asked to take a bath. Ten minutes later, as his horrified father watched, he suddenly went limp.

His father tried CPR as paramedics rushed to the west-end home.

"They worked on my son feverishly for over two hours," Frustaglio said. "His heart wasn't responding. The disease had taken over his heart."

The tragedy follows the death Saturday of a 10-year-old eastern Ontario girl from H1N1. Vanetia Warner of Cornwall, Ont., was sick for several days before her condition rapidly deteriorated.

She died Saturday in Ottawa. It was not immediately known if she had any underlying medical conditions.

The swine flu has now killed close to 100 people across Canada. Ontario has had close to 30 deaths, six of them children, since April.

Three more deaths in British Columbia over the past week raised that province's total to 12.

Most victims -- about 90 per cent -- had underlying health conditions.

"Death is a rare event, and it's a particularly rare event in young people," said Dr. Arlene King, Ontario's medical officer of health.

Why the same strain of virus can cause mild symptoms in one healthy person and be lethal in another is a mystery, although its newness may be a factor.

"We don't have all of the answers," King said. "The key thing for all of us is to try to prevent ourselves from getting infected to begin with."

Dr. David McKeown, Toronto's medical officer of health, said Evan had "mild asthma," something his father disputed.

"Evan didn't have asthma; he had been prescribed puffers a few years ago when he had a cold," Frustaglio said.

A spokeswoman for Toronto public health later said the boy did not have asthma and the earlier statement had resulted from some confusion concerning his medical records.

Mary Margaret Crapper said Evan had no underlying health issues that public health was aware of.

Ontario Premier Dalton McGuinty expressed sympathy for the family, calling it a "terrible tragedy."

The province, he said, was doing everything it could to provide a vaccination program as quickly as possible.

"I continue to have confidence in our public health officials," McGuinty said.

"They're making the right decisions, getting the vaccine into the communities as quickly as they can and respecting the order of priorities that they've put in place."

Frustaglio refused to criticize the walk-in clinic, saying he was in too much grief to think about what might have been done differently.

However, he did warn parents against complacency or thinking that patients with swine flu will show symptoms for many days before deteriorating gradually.

"This didn't even take a day and a half -- it hit my son within 10 minutes," he said.

"If any one of your children has any kind of flu-like symptoms, please don't take your eyes off of them. Make sure you get the medical attention you need and, if at any time, they don't seem right, especially with their breathing, just get medical attention."

Evan's family began taking Tamiflu after his death as a precaution and immediately informed Evan's teammates of what had happened so they, too, could seek medical attention.

Evan is survived by his brother Will, 10, and his mom, Anne-Marie, who was too distressed to speak about her loss.

"I'm really having a hard time with this," she said.

Ontario Health Minister Deb Matthews said the "very sad case" should impress on people the need to get inoculated.

"It doesn't protect just you, it protects all the people around you," Matthews said.

Evans' death sparked an outpouring of sympathy and tributes on Facebook and YouTube, with numerous pictures and even a tribute video.

One Facebook writer said she hoped the tragedy would heighten awareness of the dangers of H1N1.

"I feel for your loss; my heart aches for your sorrow," Tracey Parr wrote.

"Hope Evan's passing will heighten the awareness of this flu, and preventative measures needed to be taken."

Frustaglio called Evan a "wonderful" boy who was "full of spirit." His son had switched this year to the Hill Academy north of Toronto -- a small school with an emphasis on athletics -- because "it was all about hockey."

"My son is gone. He was here just 24 hours ago and now he's not here. He was 13. He didn't deserve to die," he said.

"Whenever you hear stories like this in the press, I say to myself, 'Oh my god, I can never imagine how I could ever live without one of my kids,' and now I'm asking myself that question."