Two young brothers from Canada are being hailed as heroes after they saved their grandmother’s life by performing CPR on her months after their mother taught them the life-saving technique.

Grayson and Kian Wu, 7 and 9, were watching television at their grandma’s house last month, and they noticed that she was not answering when they called for a snack.

“She looked really dead,” Grayson recalled of the moment he found her unresponsive on the couch. “Spit was going back into her mouth. She was grunting a little.”

It turns out that their grandma, 62-year-old Patti Chatterson, had suffered a massive heart attack and was in cardiac arrest.

“It was so scary,” Grayson remembered. “I didn’t want to let our grandma die.”

Thankfully, their mother Lee Chatterson Wu had taught the boys how to perform CPR five months before when they became interested in it after seeing it in a movie.

“There was a little boy there whose parents are medical professionals and they’ve taught their kids things like this,” said Lee, who is a nurse. “The kids were all downstairs watching a movie and I heard this little boy yell out, ‘It’s cardiac arrest, start CPR.’  So I made a big deal about it, I said, ‘You’re very smart and good job.’”

“I honestly didn’t think they’d ever need it,” she added.

Kian remembered what his mother had taught him that fateful night with his grandmother, and they started to perform chest compressions on her as they called 911.

“We just acted,” Kian said.

The boys were performing the chest compressions so hard that they cracked her ribs.

“My older grandson just felt terrible,” Patti said. “He was so, so worried because when he was doing the compressions, he heard my sternum crack.”

Paramedics arrived minutes later, and Patti ended up waking up in the hospital. She has since made a full recovery and thanked her grandsons, who she says “kept their cool so incredibly well.”

“You know what, Grandma,” she remembers Grayson telling her, “I’m not done spending time with you.”