AIRDRIE, Alta. -- An official in the community of Airdrie, just north of Calgary, says ice on a drainage canal can be deceiving and is urging caution after a little boy's death.

Wilf Richter, with Airdrie's planning and engineering department, said the overland drainage system is meant to capture rain water or snow melt and direct it away from homes in the surrounding neighbourhood.

With temperatures above zero last week, Richter said "obviously the ice got much more fragile and softer."

"You've got water melt and snow melt going on top of the ice, it makes the ice softer, and even if it doesn't go on top of the ice, it certainly flows in from underneath," Richter said in an interview Tuesday.

"And where you might have had six inches or eight inches or a foot of ice, now you might have one or two inches, but you wouldn't know by looking at it visually from above."

The six-year-old boy died in hospital Monday after he and his 10-year-old brother fell through the ice.

A woman who lives in the area called 911 after she saw the children go through the ice. Firefighters pulled the boys from the freezing water and they were rushed to hospital, but the younger boy died.

His 10-year-old brother suffered hypothermia and was in serious condition, though RCMP said his prognosis is good.

Deputy fire chief Garth Rabel called it a "horrific, unfortunate" accident. He said changing weather conditions can make ice surfaces unpredictable.

"There was ice cover, open water, very precarious ice conditions, so that's what our team found when they arrived," he said Tuesday. "There is the potential always for water to be running under in these type of water channels. Running water, of course, doesn't freeze and it can always jeopardize the ice surface as well."

Asked if the drainage canal should have been fenced off, he said no.

"You look in any community ... there is open, natural waterways or man-made waterways that manage drainage and such, and to be able to manage those all consistently with fences just isn't practical."

Rabel said, however, that as a general rule man-made ice -- either indoors or outdoors -- has either grass or concrete as its foundation and is safer as a recreational ice surface.

"Just be very, very cautious," he said. "Look out for our children, look out for our pets, look out for any movement around those waterways."