Country music star Granger Smith is mourning the loss of his 3-year-old son after he drowned in a family pool in Texas. In an Instagram post Thursday, Smith said his son River Kelly Smith died in a tragic accident, writing, "I have to deliver unthinkable news."

Drownings are the leading cause of unintentional deaths of children ages 1 to 4. It's a heartbreak former Olympic skier Bode Miller and his wife Morgan know well. They lost their 19-month-old daughter Emmy last June, when she drowned in a neighbor's pool.

"Everytime I close my eyes at night to go to sleep, it replays in my head. It happens so fast," Morgan Miller said after the accident.

Morgan showed her support for the Grangers, posting a photo and writing "My heart breaks. Another baby gone too soon."

The Millers have used their experience to raise awareness about the drowning risks for children; A tragedy that claims almost 1,000 kids a year.

Bode Miller and Nicole Hughes, another mother who lost a child to drowning, joined "CBS This Morning" last month. They've partnered with the American Academy of Pediatrics to create new PSAs, hoping their grief can teach others and help save lives.