A Saint-Lambert family is reeling following the loss of their four-year-old son, who was found unresponsive in their backyard pool Saturday.

He's the 20th person to drown in Quebec this year, with the tragedy prompting warnings about the importance of water safety.

Longueuil police (SPAL) were called to the home on Normandie Ave. at 4:10 p.m. Saturday. First responders tried to revive the boy, and he was transported to hospital, where he was pronounced dead shortly after 5 p.m.

"The family is devastated," said SPAL spokesperson Francois Boucher.

Officers say the family had a fence around the in-ground pool, and it's unclear how the four-year-old got in.

"The investigation has shown so far that this was accidental in nature," said Boucher.

With pools starting to open across the province, guardians should not take their eyes off their children for even a moment, warned Raynald Hawkins with the Quebec Lifesaving Society.

"With toddlers, it can happen in 15 to 20 seconds. It's silent," he said.

Another piece of advice: keep children within arm's reach.

"It's like crossing the street," he said. "You always want to take the kids by the hand. This is the same reality with the backyard pool."

With files from The Canadian Press.