SOMBA K'E/YELLOWKNIFE - Five figures could be seen breaking the white expanse of Frame Lake Wednesday afternoon. They scrambled across as more than one bystander slowed to watch in anticipation to see if they'd make it to shore safely.

Those people – who turned out to be adults, not children as was reported on some radio stations – were engaging in extremely dangerous behaviour, according to the city's fire department.

The department is warning residents that people who choose to walk on the city's lakes this time of year are risking their lives because the ice still isn't thick enough.

"People want to use this to cross because it's faster. But they should know, if they go through the ice, it'll take the fire department at least 10 minutes to get there. They'll be in the water for at least 15 minutes. By then, hypothermia will set in. That's what they're asking for by crossing the water when it's not safe," said Gerda Groothuizen, deputy fire chief of life safety and prevention.

The fire department recommends people wait until the ice is at least six inches thick, she said.

Last year there wasn't sufficient ice until the middle of November. Groothuizen said it's impossible to know when the city's lakes will freeze, especially as the temperature has risen above freezing some days.

"Your guess is as good as mine. It all depends on weather conditions and if we have a cold snap," she said. "Stay off the ice, the ice is not safe yet unless you're looking for trouble."

Groothuizen said there haven't been any incidents of walkers falling through the ice in several years and she hopes it stays that way.

Doug Gillard, director of municipal enforcement, said falling through the ice is entirely preventable.

"Everybody knows, just some people choose to take that risk. When they're risking their lives, they're also risking the lives of the people going out to save them," he said.

Gillard said the city has been receiving calls of people walking across lakes for weeks.

"As soon as we get the snow on the ice, I don't know if it's a sense of security when they see the snow and it's all one solid colour. I don't know but it brings them out," he said.

Gillard said depending on how much people weigh and how many people are walking, the level of risk changes.

"It's going to be a bit longer before we have ice-building weather," he said. "This is going to be going on for the next month or so, we're going to get ice on Back Bay where ice is just starting to form."

Every weekend members of the Great Slave Snowmobile Association Trail Riders test the ice thickness at various locations around Yellowknife. The results are available on the city's website.

The ice on Frame Lake near the Co-op was recorded at 4.5 inches on Oct. 23. Thickness varied in other parts of the city, from open water in Yellowknife and Back Bay, to four inches in parts of Range Lake and 4.5 inches on Niven Lake.

Groothuizen said even if ice is thick in some sections, there's no guarantee it's safe in other areas of the lake, particularly by the shore.

"Where there's flowing water from streets going into the lake stream, like Range Lake by Parker Field, it's a lot thinner," said Groothuizen.

She added people may get a sense of security from seeing footprints on the ice but that's no guarantee.