A week after seven vehicles broke through the ice of Lake Minnetonka, the Hennepin County Sheriff's Office is urging people to be careful when using county lakes for recreation.

Lake channels should be avoided by drivers as well as pedestrians, snowmobilers and people on ATVs, and pressure ridges should be avoided because the ice may be unstable, the Sheriff's Office says.

That's true even after extremely cold weather, which is expected to ebb this week. Freezing and thawing creates variable ice conditions.

The Sheriff's Office recommends that anyone using the ice wear life jackets. Adults should stay near young children at all times, and parents of teens and young adults should make safety rules and restrictions clear.

Between Jan. 18 and 21, seven vehicles went through Lake Minnetonka ice. In two of the incidents, including one in which a baby later died, someone drove in a channel. Four broke through a pressure ridge, and one went through weak ice near a culvert. Two cases resulted in DWI arrests.