HAMILTON COUNTY, TN. (WRCB) -- The parents of a Hixson High School student are singing the praises of the school staff for helping save their daughter's life.

Their 15-year-old daughter nearly died after passing out in class.

It is still a mystery what happened to freshman Katie Wood, but on the first day back to the new semester, she passed out in class and stopped breathing.

With the help of an Automatic External Defibrillator, the school nurse shocked her back to life.

"When someone has a medical emergency, we want quick response," says Hixson High Principal Lee Sims.

Sims says that is what happened last week when 15-year-old Katie Wood suddenly passed out in class.

"Her lips were blue. She was not breathing. She did not have a pulse. She was on the floor on her right side. There were no signs of life," says school nurse, Candis Vickers.

Vickers jumped into action, performing CPR, telling teachers to call 911 and had Principal Sims get the school's Automatic External Defibrillator.

"You get the machine, the pads are in here," she explains, while opening the AED.

She says her mind was racing.

"Is she breathing? Are we going to have enough time to get her to the hospital? Is she going to be ok?"

With a shock, Katie was kept stable until paramedics arrived and whisked her away to the hospital.

"Her heart is doing great. We're just still having to recover from the whole process of everything," says Katie's mom, Amy Allen.

Channel 3 talked to Katie's mother by phone, as she still recovers in the hospital.

She and doctors say Candis saved Katie's life.

"That nurse did everything she was supposed to, and she did it perfect," says Allen.

"As a mom, my heart was breaking, and I knew I had to do something for her," says Vickers. 

Candis is just glad she could help.

"I'm thankful for her health and that she's getting better," says Vickers.

"She did a good job, quick response administering the CPR, knowing when to get the defibrillator, and make that work well," says Sims.

"Thank you, is not enough. Words can never say. Thank you for saving the life of our little girl," says Allen.

Doctors are still running tests to see if Katie had a seizure or a cardiac event, but so far her tests are coming back normal while she recovers in the ICU.

Principal Sims says in light of the event, they will be brushing up on the use of the AED with all the staff.

They are also in the process of getting another one of the life-saving devices.