CHICAGO (CBS) — With bitterly cold temperatures in recent weeks comes a temptation: The belief that it’s safe enough to take a stroll on the frozen lake.

CBS 2’s Jim Williams reports lots of people are doing that and posting photos on social media.

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Those perilous walks are catching the attention of the police and fire departments, urging people to stay off the lake. Adding that looks are deceiving.

You might think it goes without saying that walking on a frozen Lake Michigan is dangerous. But the Chicago Police Department’s Marine Unit had reason to tweet this warning in all caps: DO NOT DO THIS:

Embedded in the tweet was video of people on the lake…yards from the shore. CPD added “Your life is worth more than an Instagram, Twitter post or TikTok video.

Water safety expert David Benjamin of the Great Lakes Surf Rescue Project said the frozen water may appear solid, but some parts are fragile, especially as the temperature creeps up.

“It’s unfortunately a disaster waiting to happen,” Benjamin said.

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And if you fall through, a crucial countdown to hypothermia begins.

“You have one minute to control your breathing, 10 minutes of meaningful movement, less than an hour until hypothermia may set in fully and kill you,” Benjamin said.

Even those who have no intention of walking on the ice should be careful close to the shore, as it’s hard to tell where the beach ends and the lake begins.

“And so even though you may think you’re near the pedestrian path, you could be 20 yards over the open water,” Benjamin said. “It’s best just to admire from a distance.”

The Police Marine Unit on Tuesday issued a video with a warning about staying off the ice, and what to do if you do end up falling into the water.

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In addition to the social media posts, police officers and firefighters are using loud speakers to order people off the lake.