Teen uses CPR to save baby's life in Walmart

A quick-thinking teenager helped save a baby's life in High Ridge, Missouri, on Wednesday.

Surveillance video at a Walmart store shows a desperate mother who realized her 11-month-old daughter had stopped breathing and was trying to revive her.

Abby Snodgrass, 17, heard the commotion, ran over and began performing CPR on the child.

"The one thought that crossed my mind was, 'What if this doesn't work?' And I just had to push it out of my mind and keep going because I knew that's what I had to do," said Snodgrass.

The baby started breathing again.

"I can't explain how happy I was when she started to breathe," Snodgrass said. "It was a huge relief."

Without her swift action, the infant may have died, emergency responders said.

The baby is fine and in good health.

Snodgrass says she just recently learned how to do CPR in her high school health class.

ABC News contributed to this report.