ST. LOUIS COUNTY – A St. Louis County family says their dog is a hero for waking them up during a house fire before the smoke detector alarmed.

It happened in South County early Sunday morning, around 2 a.m., when the Beaudreau family's black lab, River, wouldn't stop barking and nudging her owners.

"I'm thinking, 'What a pain in the butt. What's wrong with you dog?'” Laura Beaudreau told 5 On Your Side.

But she's glad she listened. After the dog couldn't be appeased with food or time outside, Beaudreau and her husband, Matt, got up to start looking for what was wrong.

When she opened the door to the garage, what she found was terrifying.

"Flames and black smoke and immediately slammed the door,” Matt said.

They rushed to get their two boys from the basement and their daughter from her room and left their burning home with what they could grab.

"We had our phones, and I got my bag with my laptop in it because it was by the door,” Matt said.

And watched safely from outside as the flames poured from their home, grateful for River's warning.

"River is a hero. She was sent like a guardian angel,” Laura said. “She saved our lives.”