A 12-year-old Nova Scotia girl is being hailed a hero after she used skills she learned in a babysitting course to save her grandmother’s life.

Theresa Mills and her granddaughter, Kaylee Campbell, were having lunch at Subway in New Glasgow, N.S., on Monday when Mills started to choke on her food.

“I couldn’t talk. I couldn’t breathe, so I got up and she was trying to give me a drink and I said no. I couldn’t. I didn’t say anything. I was just hitting my chest,” recalls Mills.

Realizing her grandmother was choking, Campbell knew exactly what to do and sprang into action.

“I remembered that when, from my babysitter’s course, that if someone is choking you do the Heimlich manoeuvre, and it sort of just came to me, like, out of memory,” says Campbell.

Mills says her granddaughter performed the procedure, which dislodged the piece of food from her throat.

“I was nervous but, like, out of the babysitter’s course, I knew that panicking wouldn’t make anything better, so I kind of stayed calm and did what I knew to do,” says Campbell.

The girl’s response was so quick staff barely had time to pick up the phone and call 911.

“As I was getting out of my mouth that a customer was choking, she came through,” says Amanda Richards, who works at the sandwich shop.

“She seemed to know what to do and she just did it and I could breathe and it was wonderful because I’ll tell you, it was scary,” says Mills.

Campbell learned First Aid at a babysitting course at the YMCA last year.

“It’s a good thing for anybody to learn because, being able to respond to an emergency, even if it’s the phone call, it’s helping somebody,” says Wendy Sutherland of the Pictou County YMCA.

Mills says she is grateful her granddaughter took the course, and says she’s nothing short of a hero.

“I think if she wasn’t there, well, the ambulance would have showed up eventually, but she’s certainly a hero to me,” says Mills.

“I guess I’m a hero,” says Campbell. “But, I mean, I’d do it for anybody if I knew how.”

With files from CTV Atlantic's Dan MacIntosh