A young Nova Scotia boy stayed cool under pressure and saved his sister’s life when she began to choke last week.

Ten-year-old Garrett Williams and his six-year-old sister Shanna were driving home from school with their grandparents when Shanna went into distress.

“We got picked up by my grandparents and we were on our way to their house and then Shanna started to choke,” says Garrett.

Shanna was choking on a lifesaver. The children’s grandfather stopped the car and started pressing her chest to help her breathe.

That’s when the Sutherlands River, N.S. boy stepped in and used what he learned in school to help his sister – the Heimlich manoeuvre.

“Once I seen he was trying to press on her chest, I thought ‘I don't think he's going to be able to do it. I'll have to go out and do it.’ So I went out behind her, I lifted her up and then the candy went actually quite fast right out and broke,” says Garrett.

Garrett had performed a perfect Heimlich manoeuvre on his sister.

The children’s mother Carla Williams almost couldn't believe the story.

“When my mom told me that her lips had turned blue and she wasn't able to bear weight once my dad got her out of the car and she was trying to get her fingers down her throat, then I realized that she really was choking,” says Carla.

“I knew it was serious, because I did see her lips turning blue,” says Garrett.

Garret learned the Heimlich manoeuvre by taking a St. John Ambulance course at school two years ago, called We Can Help.

“My body is just covered with goose bumps again, every time I hear the story, every time I tell the story,” says Glenna Oldford, educational assistant at Frank H. MacDonald Elementary. “It's just amazing that this precious little boy was able to retain and do what needed to be done to save his sister.”

Carla says she thinks every child should take the course.

“If something like this saves one kid's life it's worth it and it has saved Shanna's life I believe,” says Carla. “I think if Garrett wasn't there, she could have died.”

The St. John Ambulance We Can Help program is being offered at the school in just a couple of weeks’ time and given Garrett's heroic actions, registration for the course is more popular than ever.

With files from CTV Atlantic's Dan MacIntosh