Lexie Comeau-Jackson’s smile lights up the room as her mom tells the heroic tale of when this young girl found her powerful voice.

“All of the sudden, I'm upstairs and I hear her screaming bloody murder,” says Kelly Jackson, Lexie's mom.

Lexie, who lives with cerebral palsy, was able to let out a shriek that alerted her family that her baby brother, Leeland, was in trouble.

“We've never heard her scream like that,” said Kelly Jackson, a busy mom of three who was preparing for Lexie's birthday party at their Dartmouth home.

The nine-year-old was sitting in the kitchen, watching it all unfold.

“Running back and forth trying to make the food, and bring stuff outside and inside and (Leeland) was napping at the time,” Jackson said. “So then I thought OK, he's up, I'm going to run upstairs and get changed. Mom brought him downstairs for me, we didn’t communicate the door isn't locked.”

Leeland was placed in the kitchen, his grandmother turned around for a few seconds, and in a wink, he slipped out the back door.

“The scary thing is, he opened the door and closed it behind him, and he had never opened that patio door before,” said Jackson.

That's when the birthday girl became the hero.

"She's yelling and she's pointing at the door and I realize Leeland’s not with her,” said Nancy Comeau-Drisdelle, Lexie’s grandmother.

The 18-month-old boy was already heading for the backyard pool.

“I took off outside, and I’m not seeing him,” said Comeau-Drisdelle. “We had just refilled the pool, it was freezing cold, we had the tarp on top, and I ran. We didn't have this gate. I ran, he's right by the edge and I took him out.”

Leeland coughed up some water and was later taken to the hospital as a precaution.

“I hugged her, I cried, and I still thank her every day,” said Lexie’s mother. “Because honestly, in that matter, two seconds makes a huge difference.”

Within two days of the incident happening, the family installed a fence and a locked gate between the house and the pool.

The Halifax Regional Police and her MLA recognized her for her lifesaving act, and she’s proud of those awards. Her efforts will also be recognized at City Hall this week.

Lexie has proven that anyone can save a life.

“You don't need to be able to walk and talk, and have all your senses,” said Comeau-Drisdelle. “You can still make yourself heard and you can still help. And yes, she did save his life you know.”

With files from CTV Atlantic’s Heather Butts.